Note: These are the original, non-proofed versions of the
abstracts accepted for presentation at the 1996 meeting of the
Society for Psychophysiological Research to be held in Vancouver,
British Columbia, Canada. Typographical errors that may be present
in these abstracts may have been corrected at the copy-editing stage.
However, no changes -- typographical or substantive -- can now
be made, as the Abstract Supplement is already in press.
Sincerely, Margaret Bradley, 1996 SPR Program Chair
---------------------------------------------------------------
Abstracts of Papers to be Presented at the 36th Annual
Meeting of the Society for Psychophysiological Research
The Thirty-Sixth Annual Meeting of the Society for
Psychophysiological Research will be held October 16-20, 1996
at the Hotel Vancouver in Vancouver, British Columbia, Canada.
Members of the Program Committee are Margaret Bradley (chair),
Francis Gabbay, Jutta Globisch, Ottmar Lipp, Harald Schupp,
Robert Simons, Diane Swick, Cyma Van Petten, Scott Vrana and
Steven Woodward.
The program includes three invited addresses and the
Presidential Address. Specific topics will be addressed in
twelve Symposia. The majority of research reports will be
presented and discussed informally at three Poster Sessions.
This web page contains abstracts for each presentation
in the Symposia, and for the Poster Sessions. The Symposia
are printed in the order in which they will occur at the
conference. The Poster Session abstracts are published
together in alphabetical order by first author.
These abstracts will be published and distributed to
all members of the Society in a supplement to the journal
PSYCHOPHYSIOLOGY.
---------------------------------------------------------------
Invited Speakers
Patricia Churchland, University of California-San Diego
Towards a neurobiology of consciousness
John Gottman University of Washington
What predicts divorce? Building a theory
Marta Kutas, University of California-San Diego,
Presidential Address
Meeting language head on: Constraints from anatomy, meaning,
physiology, and structure
Michael Merzenich, Keck Center for Integrative Neuroscience,
San Francisco
Specific language impairments: Neurological origins, and an
effective neurologically-based therapy.
---------------------------------------------------------------
THURSDAY MORNING
Symposium 1
Off to the Races: Ethnicity in Contemporary
Psychophysiology
Chair: Robert F. Simons
Participants: Robert F. Simons, Scott Vrana, Cheryl
Armstead,
Eric Vanman, Jeanne Tsai
Discussant: Gregory A. Miller
A paper presented recently at a meeting of the American Lung
Association (Glindmeyer, 1996) reported that women who quit
smoking and remained 'smoke free' regained significant
breathing capacity, supporting the clinical observations
that some tobacco-related damage to lung tissue is
reversible. Perhaps more striking, however, was the
additional finding that this recovery applied only to white
subjects. Black women, also smoke free for 20 years, failed
to regain any breathing capacity as a result of their
abstinence from smoking.
This report illustrates, as well as any in the
literature, the importance of race and ethnicity as a topic
for psychophysiological investigation. What could account
for such striking between-group differences? Fundamental
differences in anatomy or physiology? Ancillary differences
in attitudes, life events or emotion-processing that vitiate
the effects of smoking cessation?
In juxtaposition to this provocative study and the many
questions it raises, a survey of the literature undertaken
to examine the frequency of appearance of ethnicity in
psychological research (Graham, 1992), reported that such
studies are on the decline. This juxtaposition is cause for
concern. Representation of diverse subject groups in
psychophysiological research and the inclusion of ethnicity
as a substantive independent variable will be necessary in
order to understand the type of finding reported by
Glindmeyer and by others.
The present symposium consists of five presentations
involving ethnicity, racial attitudes, and human emotion.
Though the overarching theme of ethnicity is consistent
across studies, there is considerable diversity in both
method and approach. These experiments reveal a number of
emotion-related differences among Black-, White- and Asian-
American subjects while at the same time illustrating some
interesting and sometimes surprising similarities.
RACE-OF-EXPERIMENTER REDUX
Robert F. Simons
University of Delaware
Over forty years ago it was reported by Rankin and Campbell
(1955) that experimenters of an opposite race (black)
provoked increased arousal in subjects (white). Though this
experiment had serious limitations (Petty & Cacioppo, 1983),
it has nonetheless become part of the psychophysiological
lore. The present experiment attempted to put the race-of-
experimenter hypothesis to a more rigorous test by employing
multiple measures, by employing multiple experimenters, by
counterbalancing both experimenter and subject race, and by
examining racial attitudes held by subjects.
Both Caucasian (high- and low-'racist') and African-
American subjects participated in the present two-part
experiment. Part 1 consisted of the greeting, explanation,
informed consent and psychophysiological 'hookup', all
conducted by a same-race experimenter, and then the
unexpected introduction of a laboratory assistant of either
the same or the opposite race who would conduct the
remainder of the experiment. Facial EMG, heart rate and
skin conductance were measured as the assistant conducted a
brief demographic interview and then conspicuously touched
the subject while allegedly checking the quality of the
electrode placements. Part 2 consisted of a standardized
interview which required subjects to address topical issues
that were either stereotypically race relevant or race
neutral. Lastly, subjects were asked to provide affective
reactions to both the experimenter and the assistant.
Black assistants prompted greater HR and SC reactivity
from their subjects, and this was true during both phases of
the experiment. Surprisingly, this effect was as strong and
sometimes stronger among African-American than it was among
Caucasian subjects. The racism measure was unrelated to
physiological reactivity, though it did predict their
affective ratings of the black and white assistants.
PHYSIOLOGICAL RESPONSES TO SOCIAL AND EMOTIONAL CONTEXTS IN
BLACK AND WHITE AMERICANS
Scott R. Vrana
Purdue University
Two assumptions about differences in social and emotional
responses of Black Americans and White Americans have
received inadequate empirical test: that African Americans
are more emotionally expressive because of the values of
their African cultural heritage; and that Black Americans
find interethnic interaction particularly stressful, and
this stress contributes to Blacks' high levels of chronic
stress and hypertension.
These assumptions were examined by having both Black
and White college students participate in emotional imagery
and a neutral in vivo interaction with people of the same
and different ethnic background. Facial EMG (corrugator,
zygomaticus) and cardiovascular measures (heart rate, blood
pressure) were recorded. Facial EMG results showed that
White subjects displayed a very positive expression in a
social greeting, whereas Black subjects exhibited a more
neutral expression. In contrast, compared to White
subjects, during imagery Black subjects displayed a higher
baseline zygomatic and greater smiling during joy imagery;
and showed a lower corrugator baseline and less frowning
during negative imagery. The imagery study replicated
earlier blood pressure differences between Black and White
Americans: Blacks had a higher resting blood pressure and
greater increases while listening to the emotional imagery
script. However, in contrast to the hypothesis stated
above, it was White subjects (especially White males) who
exhibited the greatest cardiovascular response (increased
heart rate and blood pressure) to interethnic interaction
(greeting and being touched by a Black male).
These results will be discussed in terms of their
implications for interethnic relations and the social
context of emotion.
PSYCHOSOCIAL PREDICTORS OF CARDIOVASCULAR RESPONSES TO A
RACIAL SPEECH STRESSOR
Cheryl A. Armstead1, Kathleen C. Lawler2, Norman B.
Anderson3, and Chy Relle Thompson1
1University of South Carolina ,2University of
Tennessee,3Duke University Medical Center
There is a growing body of literature identifying racism as
a stressor eliciting acute changes in cardiovascular
functioning in the laboratory. Laboratory speech stressors
may yield important qualitative information concerning
perceptions of racism and behavioral styles utilized in
coping with racism. The present study examined the
influence of emotional and psychosocial factors on
reactivity and recovery to a racism speech stressor.
Thirty African American normotensive females were
administered a 10 minute racism speech stressor, with blood
pressure measurements taken speech and during recovery.
Stepwise regressions, with measures of anger as
predictors,were performed for the speech task and during
recovery. Several anger measures (e.g. expressed hostility,
habitual failure to suppress anger) predicted diastolic
reactivity to the racism speech stressor while other
measures (educational attainment) predicted diastolic
recovery from the speech task. Likewise, the same, or
closely related measures predicted reactivity and recovery
of the mean arterial blood pressure measure. There were no
significant anger-associated predictors of systolic blood
pressure responses.
These preliminary analyses suggest that cardiovascular
reactivity to a racially salient stressor is influenced by
both experienced and habitual emotional coping styles among
African-American females. Educational attainment and anger
suppression were consistently predictive of degree of
recovery after this acute racial stressor. Thus,
educational level may be associated with attenuations of
autonomic arousal after the task. These results underscore
the importance of assessing qualitative aspects of racism-
related laboratory stress responses among African-Americans.
AFFECTIVE AND ATTENTIONAL COMPONENTS OF RACIAL BIAS USING
FACIAL EMG AND THE BLINK REFLEX
Eric Vanman1 and Tiffany Ito2,
1University of Southern California, 2The Ohio State
University
Previous research demonstrates that facial EMG can reliably
index racial bias, even when self report measures cannot.
The growing popularity of the startle eyeblink reflex as a
measure of affective response suggests that it too might
serve as a marker of such bias. In this study we recorded
facial EMG from the brow, cheek, and eye regions while
White,Asian, Hispanic, and Black participants viewed
pictures of White and Black students. For one half of the
trials participants were instructed to attend to the
duration of the black (or white) slides, and for the other
half were told to ignore the duration of the white (or
black) slides. During some trials an acoustic startle probe
was presented at either 300, 800, or 4500 ms following slide
onset. Analyses revealed evidence of racial bias as a
function of the participant's race. For the Asian and White
participants, cheek EMG activity was greater for White
targets and brow activity was greater for Black targets.
For these same participants, startle eyeblink amplitudes
were greater when White targets served as prepulses at 800
and 4500 ms. The Hispanic and Black participants tended to
demonstrate the opposite pattern. However, at 300 ms probes
all participants exhibited more startle reflex inhibition
for attended prepulses, regardless of the target's race.
These findings indicate that in this paradigm the startle
eyeblink reflex is more sensitive to attentional processes,
whereas facial EMG is more sensitive to affective processes
in racial bias. We discuss implications for research in
intergroup relations.
EMOTION AND PHYSIOLOGY IN ASIAN AND EUROPEAN AMERICAN
CULTURES
Jeanne L. Tsai and Robert W. Levenson
University of California, Berkeley
Notions that culture influences emotional responses are
wide-spread. For example, compared to European Americans,
members of Asian cultures are believed to demonstrate
greater emotional moderation, somatize their emotional
states more, and base their emotional states more on the
interpersonal nature of the social context. Few studies
have examined whether the two groups differ in actual
emotional responding,and if so, whether such differences are
consistent with these notions. Studies in our laboratory
have compared emotional responses (autonomic and somatic
physiology; dimensional and discrete emotional self-
reports) in a variety of Asian and European American
cultures using both intrapersonal (films, loud noises, and
voluntary emotional facial expressions) and interpersonal
(dyadic interaction) stimuli.
In this work we have found little evidence that
purported emotional moderation in Asian cultures extends to
the physiological level in either intrapersonal or
interpersonal contexts. However, in both contexts, Asians
have demonstrated greater emotional moderation in reported
subjective emotional experience. Cultural differences have
also been found in relationships between physiology and
subjective experience. For both Asians and European
Americans, physiological and subjective emotional responses
were correlated when emotions were elicited in interpersonal
contexts. In intrapersonal contexts, these correlations
were found for European Americans, but not for Asians.
A model of how culture influences the physiological and
subjective aspects of emotional responding will be
discussed, highlighting the role of the social context as a
mediator of cultural influence. Our findings will be used
to evaluate empirically several key ethnographic notions
about emotion in Asian cultures.
Symposium 2
The Lateralized Readiness Potential: Contributions
to the study of information processing
Chair: K. Richard Ridderinkhof
Participants: Michael G. H. Coles, K. Richard
Ridderinkhof, Martin Eimer, Fernando Valle-Inclan
Discussant: Michael G. H. Coles
In recent years, the lateralized readiness potential (LRP)
has been extremely fruitful in exploring the structural and
temporal aspects of the human information processing system.
The LRP has proven to be a reliable and highly sensitive
real-time index of the relative activation of competing
responses in a variety of experimental tasks, and can reveal
whether and when a particular response is preferentially
activated. The present symposium is intended to provide an
overview of the history and ideas behind the LRP, of
methodological pittfalls and innovations, and of recent
empirical results and their implications. The presentations
of experimental work will focus in particular on how
irrelevant stimulation (distractor arrows, locational cues,
and subliminal primes) exerts its effect on the processing
of target information. In one study, LRP evidence indicates
that distractor arrows prime response activation processes
directly, without undergoing controlled response selection
first. The response thus activated is subsequently
inhibited when the target stimulus signifies that the
subject should refrain from responding. In the second
study, LRP evidence reveals how the response to a target
stimulus is impeded by the presence of an identical
subliminally presented prime stimulus. The subliminal prime
briefly activates its corresponding response, which is then
strongly inhibited. In the third study, LRP evidence
emphasizes the role of a central decision mechanism rather
than automatic response activation when the irrelevant
stimulation is spatial in nature. Together, these LRP
studies yield important new insights into the processing
architecture and temporal dynamics of interference from
irrelevant information.
THE LATERALIZED READINESS POTENTIAL: PAST, PRESENT AND
FUTURE
Michael G. H. Coles
University of Illinois at Urbana-Champaign
In this presentation, I will consider the use of measures of
the lateralized readiness potential (LRP) in the study of
human information processing. The LRP provides an
indication of the relative activation of two responses
(usually the left- and right-hands), and, when measured
appropriately, can reveal whether and when a particular
response is preferentially activated. The measure has been
used to explore the architecture and dynamics of the human
information processing system. Particular insights have been
gained into the nature of information transmission, and the
measure has been especially successful in specifying the
cognitive locus of various kinds of interference effects and
in characterizing the effects of aging on cognition. Issues
still in need of resolution concern the measurement of the
onset latency of the LRP, and the interpretation of LRP
amplitude.
LRP EVIDENCE FOR DIRECT RESPONSE-ACTIVATION EFFECTS OF
TO-BE-IGNORED ARROW STIMULI
K. Richard Ridderinkhof1, Emil R. Lauer1, and Remco H.J.
Geesken2
1University of Amsterdam , 2Free University of Amsterdam
Responses to target stimuli are typically delayed when
irrelevant arrow stimuli point in the incorrect direction.
Recent behavioral evidence indicates that central S-R
translation processes operate on target information but not
on distractors: A right-pointing distractor always primes
the right-hand response, even when subjects are required to
respond to a right-pointing target arrow with a left-hand
(incompatible) response. Thus, distractor arrows are thought
to by-pass controlled response selection.
Two LRP studies used an arrow version of the Eriksen
flanker task to examine this assertion. Transient effects
on response activation manifestthemselves in LRP
lateralization. Typically, with a left-pointing target,
right-pointing distractors briefly activate the right-hand
response, as indicated by incorrect (subthreshold) LRP
lateralization just prior to the opposite lateralization
that precedes the left-hand response to the target. This
transient LRP effect is known as the Gratton-dip.
In the first experiment, it was shown that the Gratton-
dip was greatly attenuated when a left-pointing target
required a right-hand (incompatible) response. In the
second experiment, it was shown that on incidental NoGo
trials, right-pointing distractors initially activated the
right-hand response, even though instructions required
incompatible responses. LRPs showed further that this
initial right-hand response activation turned into
subsequent inhibition of that response once the target was
identified as a NoGo stimulus. Together, these findings
indicate that distractor arrows primed responses directly
without undergoing controlled S-R translation processes
first.
MOTOR ACTIVATION AND INHIBITION PROCESSES ELICITED BY
SUBLIMINAL PRIME STIMULI
Martin Eimer
University of Munich
A series of experiments is reported where target stimuli
were presented requiring either a left-hand or right-hand
response. Prior to the target, a masked prime stimulus was
delivered that was either identical to the target
(compatible trials) or was identical to the alternative
target stimulus (incompatible trials). Subject's verbal
reports and forced choice performance indicated that they
were not consciously aware of the presence of the prime
stimulus. However, behavioral performance was strongly
influenced by the prime, with faster RTs and less response
errors in incompatible as compared to compatible trials.
The Lateralized Readiness Potential (LRP) waveforms revealed
the mechanisms responsible for these unexpected effects: An
initial activation of the response indicated by the prime
was found, which was then followed by a strong inhibition
process; this latter process resulted in a partial
activation of the response side opposite to the side
indicated by the prime, thereby giving rise to the observed
behavioral effects. Further experiments showed that these
effects are critically dependent on the eccentricity of the
masked prime, since they were only present with foveal prime
stimuli. A tentative functional interpretation of the
'activation-plus-inhibition' pattern and the cental-
peripheral asymmetry will be offered.
EFFECTS OF IRRELEVANT STIMULATION ON CHOICE REACTION TIME
TASKS AS INDEXED BY THE LATERALIZED READINESS POTENTIAL
Fernando Valle-Inclan
University of La Coruna
In three experiments the lateralized readiness potential
(LRP) was used to test current theories regarding the
effects of task-irrelevant information on choice reaction
time (RT). The first study tested the hypothesis that the
influence of irrelevant spatial information on RT (the Simon
effect) is due to automatic activation of the ipsilateral
(to stimulus location) response. By presenting the response
key labels after the stimulus, we showed that such
activation is not automatic.
In Experiment 2 we used a a visual search task and
manipulated the proportion of trials in which stimulus and
response locations were contralateral (incompatible trials).
We found that the Simon effect decreased as the frequency of
such incompatible trials increased. The LRP onset latencies
mirrored the RT data and there were no signs of incorrect
response activation on incompatible trials. This latter
finding indicates that spatial and nonspatial information
was available for response preparation at the same time, or
alternatively, that the interference was produced before the
LRP onset.
Experiment 3 used LRP and EMG recordings to compare two
current theories about whether the locus of the accessory
stimulus effect is at a central decision stage (Posner,
1978) or at a peripheral motor locus (Sanders, 1980). The
results indicated that irrelevant accessory stimulation
affected processes preceding the LRP onset, in agreement
with the central decision mechanism hypothesis.
THURSDAY AFTERNOON
Symposium 3
Motivated attention
Chair: Gudrun Sartory
Participants: Arne Ohman, John T. Cacioppo, Don M. Tucker,
Peter J. Lang
In the laboratory, selective attention is often conceived of
as a rational, cognitive activity that is manipulated and
investigated by instructions, by varying the probability of
stimulus events, or by altering the stimulus array to
include 'oddballs' that draw attention. In the natural
world, however, attention to one type of stimulus rather
than another may often be dictated by the organism's
existing motivational state - by drives related to hunger,
sexual arousal,and threat. The speakers in this symposium
present data and theory relevant to the thesis that
attentional processes are enlisted in the service of
processing stimuli that have motivational significance,
compared to routine, affectively neutral events.
PREATTENTIVE CONTROL OF ATTENTION TO EMOTIONAL STIMULI
Arne Ohman
Karolinska Institute and Hospital
Functional considerations suggest that motivationally
relevant stimuli should be detected after a preliminary
analysis by early, parallel processing mechanisms for
stimulus recognition. This proposition receives support from
several lines of evidence. First, research from my
laboratory has demonstrated that autonomic responses can be
elicited by stimuli that are prevented from reaching
conscious recognition by the technique of backward masking.
Thus,we have reported that phobics show elevated skin
conductance responses to masked phobic stimuli, and that
similar masking-resistant responses can be classically
conditioned in normals, provided that the conditioned
stimulus is fear-relevant. Second, visual search experiments
in which the subjects look for deviant stimuli in matrices
of stimuli demonstrate that normals are quicker to discover
fear-relevant stimuli against a background of fear-
irrelevant stimuli than vice versa. This effect is enhanced
if the subject actively fear a stimulus. For example, snake
phobic are faster to locate snakes than spiders against
fear-irrelevant backgrounds, even though they are faster
with spiders then with fear-irrelevant control stimuli.
Finally, contrary to the original report of the "face-in-
the-crowd effect", normals often are quicker to find happy
than angry faces against a background of neutral faces.
However, in a series of studies using schematic facial
expressions,which allows precise experimental control of
differential features in emotional facial expressions, we
demonstrated that angry faces are more quickly located than
happy faces, regardless of background condition. Thus, it
appears that emotional stimuli are effective in capturing
attention and in very rapidly activating psychophysiological
responses.
MOTIVATED ATTENTION: THE VIEW FROM A DUAL PROCESS MODEL OF
MOTIVATION
John T. Cacioppo
The Ohio State University
All organisms must be capable of differentiating hostile
from hospitable stimuli to survive. Typically, this
evaluative discrimination, which governs attentional
processes, is conceptualized as being bipolar (hostile-
hospitable). This conceptualization is evident in the areas
of affect and emotion, where bipolar measures and
experimental conditions focus on net affective
predispositions. Contrary to conceptualizations of the
motivational processes underlying affect as bipolar,
evidence suggests that distinguishable motivational systems
underlie assessments of the positive and negative
significance of a stimulus. Thus, a stimulus may vary in
terms of the strength of positive evaluative activation and
the strength of negative evaluative activation it evokes.
Low activation of positive and negative evaluative processes
by a stimulus reflects neutrality or indifference, whereas
high activation of positive and negative evaluative
processes reflects conflict and ambivalence. As such,
affect can be represented more completely within a bivariate
space than along a bipolor continuum. A model (Cacioppo &
Berntson, 1994; Cacioppo, Gardner, & Berntson, 1997) is
discussed in which the positive and negative motivational
processes underlying affect and emotion are distinguishable
(stochastically & functionally independent), are
characterized by distinct negatively accelerating activation
functions (marginal utility functions, positivity offset, &
negativity bias), are related differentially to ambivalence
and conflict, have distinguishable antecedents
(heteroscedacity), are activated to maximize behavioral
adaptation (modes of evaluative activation), tend to
gravitate from a bivariate toward a bipolar structure when
the underlying beliefs are the target of deliberation or a
guide for behavior (principle of motivational certainty),
and reflect individual differences in motivational
orientation.
MOTIVATED ACTION: DUAL LIMBIC SUBSTRATES OF WORKING MEMORY
Don M. Tucker1 and Phan Luu2
1University of Oregon & Electrical Geodesics, Inc,
2University of Oregon
For behavior to be organized effectively requires motivated
attention. Adaptively significant goals must be represented
within working memory so that they shape ongoing action
plans. The connections between the motivation and memory
functions of limbic cortex and the motor planning functions
of frontal neocortex must be fundamental to this process.
The densely interconnected paralimbic cortices may serve to
maintain a global motivational context within which specific
actions are articulated and sequenced within frontal
neocortical networks. The paralimbic networks represent the
visceral and kinesthetic information that is integral to the
representation of the bodily self. In a geneal sense, the
implicit self-representation within paralimbic networks may
shape the significance of perceptions and the motivational
context for developing actions. The network architecture of
the frontal lobe reflcts the dual limbic origins of frontal
cortex, in the dorsal archicortical and ventral
paleocortical structures. The dorsal limbic mechanisms
projecting through the cingulate gyrus may be influenced by
hedonic evaluations, social attachments, and they may
initiate a mode of motor control that is holistic and
impulsive. In contrast, the ventral limbic pathway from the
amygdala to orbital frontal cortex may implement a tight,
restricted mode of motor control that reflects adaptive
constraints of self-preservation. Each of these motor
pathways may elaborate a unique mode of working memory that
allows limbic motivational controls to shape the executive
attentional functions of the frontal lobe.
ATTENDING AND DEFENDING: A MOTIVATIONAL ANALYSIS
Peter J. Lang
University of Florida
Human attention is viewed here as information processing
that involves procedures of selection, sustained focus, and
the evaluation of motivationally relevant input, similar to
that occurring in an animal as it forages in a field,
encounters others, pursues prey or sexual partners, and
tries to avoid predators and comparable dangers. This
evolutionary conception of attention also defines the bio-
behavioral context in which Pavlov (1927) originally
proposed the concepts of orienting and defense. Both fMRI
and ERP research strongly implicates sites in the cerebral
cortex in the executive attentional functions of orienting.
On the other hand, animal research has emphasized deeper
structures (amygdala, limbic system, hypothalamus, and
central gray) as the foundation of primary motivational
systems that determine the direction and vigor of action--
appetitive approach and defensive withdrawal. Orienting
occurs under moderate motivation, similar for pleasant or
unpleasant input, in a cortically active but overtly
passive organism. Increased imminence of an aversive event
prompts a staged shift from passive attention towards
action mobilization, orchestrated by the sub-cortical
motivational circuits. The initial defensive reaction does
not, however, involve stimulus rejection or "a shutting
down of the analyzers." It involves more focused attention
evaluation-- part of a staged defensive process from broad
orienting to physiological mobilization and active fight or
flight. Thus, within the usual range of human
experimentation, increases in the "intensity" of a threat
stimulus (e.g., judged negative valence and arousal) are
accompanied by ERP and autonomic responses consistent with
an enhanced attentional set.
Symposium 4
Psychophysiological correlates of visual-spatial
information
processing and its contribution to performance
Chair: Edmund Wascher
Participants: Steven J. Luck, George R. Mangun, Edmund
Wascher, Shuhei Yamaguchi
Electrophysiological correlates of visual spatial attention
can be measured over the temporo-parietal cortex both as
alterations of early ERP-components (e.g. P1, N2) and as
event-related asymmetries in early time windows
independently from discrete ERP-components. The use of brain
imaging techniques permits the localization of attention-
related activity in the human brain. However, visual spatial
attention is important both for the perceptual and the motor
system. The importance of intracortical communication based
on visual spatial attention becomes evident in the deficits
of neurological patients. Not only by destruction of
posterior parietal areas of the human brain but also by
degeneration of projection deficits of neurological
patients. Not only by destruction of posterior parietal
areas of the human brain but also by degeneration of
projection pathways (e.g. in Parkinson's disease) responding
to spatial information can be impaired.
VISUAL ATTENTION AND ERPS: BRIDGING THE GAP BETWEEN MONKEYS
AND HUMANS
Steven J. Luck
University of Iowa
A detailed characterization of the neural mechanisms of
visual selective attention will require an integration of
human psychophysical experiments and monkey single-unit
recordings, but such an integration is made difficult by
many factors. ERP recordings can help to bridge the gap
between the human and monkey domains by providing a means of
assessing neural activity in humans. We have recently
conducted two sets of experiments that were designed to
provide direct links between human ERP and monkey single-
unit recordings. In one set of experiments, we adapted an
ERP attention paradigm for use in monkeys to determine the
relationship between attentional modulations of single-unit
activity in area V4 of extrastriate visual cortex and
previously observed modulations of sensory ERP responses.
Significant differences were observed between the V4
attention effects and the previous ERP attention effects,
suggesting that these effects are not homologous. In a
second set of experiments, we adapted a single-unit
attention paradigm for use in human ERP recordings to
determine whether a specific human ERP component --the
"N2pc" wave -- reflects an attentional suppression effect
that has previously been observed in monkey single-unit
recordings. Several experimental manipulations that had
previously been performed in single-unit experiments were
found to have analogous effects in the ERP recordings,
suggesting that the N2pc wave may indeed reflect the same
attentional suppression effects observed in the single-unit
recordings. Implications for attentional mechanisms and
cross-modality/cross-species integration will be discussed.
COMBINED PET AND ERP MEASURES OF VISUAL SPATIAL ATTENTION
DURING FORM DISCRIMINATION AND LUMINANCE DETECTION
George R. Mangun
University of California, Davis
In earlier research, we combined event-related potentials
(ERPs) and positron emission tomography (PET) in studies of
visual selective attention to spatial location (Heinze et
al., 1994). We found activations in human extrastriate
cortex (fusiform gyrus) contralateral to the attended
hemifield, and related this to ERP attention effects in the
occipital P1 component (latency of 80-110 msec). Here, using
the 15O-water PET method and 3-D acquisition, we extend
these findings by showing that attentional activations at
the border of the fusiform and lingual gyri were defined by
spatial selective attention and not higher-order task
requirements. A slight tendency for the fusiform activity
and the P1 component of the ERP to be greater in magnitude
during form discrimination (symbol matching) as compared to
luminance detection (detect illuminated pixels) was
obtained, and is interpreted as resulting from differential
spatial attention allocation policies used in the two tasks.
In addition to the fusiform activations, the present
findings also included activations in the middle occipital
gyrus contralateral to the attended location. The present
findings significantly strengthen our hypothesis of close
associations between early ERP attention effects and neural
activity in the human extrastriate cortex. Specifically,
they identify an early, spatially defined selection process
that acts to modulate signals from attended regions of the
visual field. The relationship of the P1 attention effect to
the posterior fusiform activations versus the lateral
occipital activations is investigated using integrated
modeling of ERP and PET activity. [This work was supported
by NSF, NIMH, NINDS, the James S. McDonnell Foundation, and
a UC Faculty Research Grant].
ŅEVENT-RELATED LATERALISATIONS" OF THE EEG REFLECT A SHIFT
OF SPATIAL ATTENTION BOTH FOR INPUT AND FOR OUTPUT CHANNELS
Edmund Wascher
Medical University of Luebeck
In a series of studies, the relationship between movement-
and stimulus-related processes was investigated. Lateral
presentation of relevant information facilitates manual
responses if the side of relevant information corresponds to
the side of the response. Analogously, manual responses are
disfacilitated if the spatial position of stimulus and
response interfere. As a psychophysiological correlate for
this interaction an increase of negativity contralateral to
the relevant information was found in the EEG over temporo-
parietal sites. This event-related asymmetry was found at
central sites (over the motor cortex) as well. However, it
was markedly smaller. This early asymmetry (200 - 300 ms)
might reflect a shift of visual spatial attention in common
with a shift of motor spatial attention towards the source
of stimulation. This shift of attention influences the
execution of a manual response. Previous studies showed that
this interaction is restricted in time, i.e. the
facilitation/disfacilitation of manual responses is not
visible if the task is more difficult (if basic response
times are longer). However, in a new task where the subjects
had to search in a stimulus array for the relevant
information, the effect on manual response times was visible
although response times were markedly prolonged in one
condition. The early asymmetries indicated that the shift of
spatial attention was delayed to the same amount as basic
response times. Therefore, there is accumulating evidence
that the interaction of stimulus- and response-related
processes due to spatial information is reflected in phasic
asymmetries of the EEG. These asymmetries most probably
reflect a controlled shift of spatial attention which is not
restricted to the perceptual system.
ELECTROPHYSIOLOGICAL ANALYSIS OF VISUOSPATIAL ATTENTION
SHIFT
Shuhei Yamaguchi
Shimane Medical University
Brain cortical activities involved in visuospatial attention
shift were studied by recording event-related evoked
potentials (ERPs) during a cued priming task. Dopaminergic
contribution on the activities were also investigated.
Normal subjects and patients with Parkinson disease (PD)
were studied in the task with a central and peripheral cue.
Attention shift-related negativities (ARNs) were generated
at the posterior scalp sites contralateral to the shifting
direction in the early stage, and at the anterior sites in
the late stage after the central cue onset. The PD group
showed a marked reduction of the ARN over the frontal site
while the posterior ARN was delayed in onset compared to the
normal group. The peripheral cue enhanced the N1 component
over the contralateral posterior cortices. The late ARN was
observed over the posterior cortices 500 ms after the
peripheral cue onset. The ARN for the peripheral cue was
normal in the PD group. However, behavioral and ERP data
showed impairment of "inhibition of return" in the PD group.
The present study suggests that distinct neural systems are
involved in voluntary and automatic attention shift.
Anterior and posterior attention systems may contribute to
the different stage in voluntary attention shift mechanism.
Mesocortical dopaminergic projection to cerebral cortex may
play a role for modulating the anterior attention network.
FRIDAY MORNING
Symposium 5
Time-frequency analysis of event-related brain
dynamics
Chair: Scott Makeig
Participants: Scott Makeig, Niels Birbaumer, Bin Shen,
Astrid Von Stein, Wolfgang Klimesch
Currently, the predominant analysis tool for studying event-
related electrical and magnetic brain dynamics is time-
domain response averaging. Its products (ERPs, ERFs) reveal
brain activity reliably locked in both time and phase
(positive or negative) to reference events. However, time-
and phase-locked activity is only one class of event-related
brain dynamics. Another class, event-related changes in
power and/or coherence of the ongoing EEG or MEG spectrum,
occur over a wide range of frequencies (~1-100+ Hz) and time
scales (msecs-minutes), and can be measured by averaging
time-frequency transforms of event-related EEG or MEG
epochs. Narrow-band (ERD/ERS) measures of changes in EEG
spectral amplitude have been in use for many years; full-
spectrum time-frequency amplitude and coherence transforms
are newer research tools. Time-frequency averages measure
event-related perturbations or modulations of the spectral
character of the EEG/MEG itself, whereas evoked responses
typically amount to only a small fraction of the recorded
brain signals. Like ERPs, time-frequency transforms vary
both with cognitive state and with stimulus significance.
They reveal cognitive event-related brain dynamics lasting
longer than the maximum (<1s) latency of most (>DC) ERP
phenomena, and thus are prime candidates for relating to
concurrent changes in brain blood flow. The symposium will
give a technical overview and survey current work in this
emerging research area.
EVENT-RELATED SPECTRAL PERTURBATIONS
Scott Makeig1,2 and Tzyy-Ping Jung1,3
1Naval Health Research Center, 2University of California at
San Diego,
3The Salk Institute for Biological Studies
From Berger's very first EEG reports, nonstationarity in the
spectral character of the EEG, as well as apparent
consistency in the EEG spectral changes accompanying changes
in wakefulness and attention were noted to be outstanding
traits of EEG signals. In 1977, Pfurtscheller described a
method of averaging the time course of event-related
reductions in power in a narrow frequency-band and called
the phenomena event-related desynchronization (ERD). During
the last decade, increasing observations of subcortical
brain centers which modulate spontaneous and event-related
cortical activity, and suggestions that subcortical and
cortical oscillations may serve to transiently synchronize
or 'bind' activity in separate brain areas have fueled
interest in observing the dynamics of EEG/MEG modulation and
synchronization processes noninvasively in humans. Makeig
(1993) demonstrated that averaging broad band time-frequency
transforms of event-related EEG epochs in an auditory
attention experiment revealed precisely-timed, both narrow-
and wide-band perturbations in the power spectrum of the
ongoing EEG, phenomena called event-related spectral
perturbations (ERSPs). ERSPs need not fit into
traditionally-defined frequency bands, and often exceed the
durations and latencies of supra-DC components of
event-related potentials. Time-frequency averaging may be
accomplished by several methods (FFT, wavelet and Wigner
transforms, matching pursuit, etc.) Both electric and
magnetic spectral perturbations have definitely been shown
to depend on cognitive processing as well as on stimulus
character, and may represent both transient amplitude
modulation of ongoing brain activity, or transient changes
in synchronization of activity in previously desynchronous
brain areas.
EVENT-RELATED GAMMA BAND ACTIVITY INDICATES BINDING IN
HEBBIAN CORTICAL NETWORKS
N. Birbaumer, F. Pulvermueller, W. Lutzenberger and H.
Preissl
University of Tuebingen
In a series of experiments with meaningful and non-
meaningful visual and verbal stimulus material the
hypothesis of a functional role of high frequency brain
oscillations for the construction of meaning was tested.
EEG-frequency bands were analyzed in 10 Hz wide windows
between 10 and 80 Hz in the time-frequency domain as
described by S. Makeig. In the visual modality, an irregular
pattern of horizontal lines in the four visual fields
changed into an orderly Gestalt-like pattern (waterfall
appearance). Over occipital cortices only, spectral power in
the 35-45 Hz frequency band increased significantly during
the gestalt-like patterns. A similar effect was seen in the
25-35 Hz range over left perisylvian cortices for meaningful
words in comparison to meaningless pseudowords. These data
support a Hebbian model of Gestalt processing in the brain
as deduced from animal experiments with simultaneously
moving visual stimuli (Singer 1995).
Supported by the German Research Society (DFG).
CHARACTERIZATION OF P3 USING MATCHING PURSUIT
B. Shen1,2 and John J. B. Allen3
1New Jersey Neuroscience Institute, 2JFK medical center,
3University of Arizona
To enhance the signal-to-noise ratio, event-related
potentials (ERPs) are often averaged over many trials of
repeated stimuli. However, this approach presumes that
cognitive processes remain stationary over those trials,
which may not be valid in many experimental paradigms.
Traditional single-trial methods are heuristic and have
failed to extract information from noisy signals reliably. A
recently developed technique, matching pursuit (Mallat and
Zhang, 1993), offers adaptive time-frequency decomposition
and has been shown to be effective in hippocampal EEG
analysis (Shen et al., 1995) and ERP studies (Allen et al.,
1995). In this study, we use matching pursuit analysis to
study the statistics and the time frequency character of the
classic P3 components of the ERPs in a memory-assessment
task. The P3 was mathematically modeled by an adaptive
Gaussian waveform while oscillatory wavelets were screened
out. This method offered a better measure of P3s because its
signal-to-noise ratio of a single-trial ERP was larger. The
statistics of the amplitudes, the latencies and the
durations of single-trial P3s were more informative than the
averaged ERP amplitudes. The correlation between the P3s
and other time-frequency components suggested that there
existed a distinct time-frequency character of the P3
components. This approach provides a new method for
examining ERP data, and a means of accessing the non-
stationarity of cognitive processes.
STIMULUS INDUCED COHERENCE: A MEASURE FOR INTERAREAL
SYNCHRONIZATION
Astrid von Stein
University of Vienna, Austria
A paradigm shift has occurred in Neurobiology. The old
concept of single cell coding is being replaced by coding in
distributed neuronal cell ensembles. results from cat
intracortical recordings have shown that synchronization
among the members of a cell ensemble play a major role in
this process. This makes it desirable to measure
synchronization also in humans. In my talk I will show that
synchronization of neuronal cell ensembles can be detected
in the frequency components of human scalp EEG. According to
our results, spectral power in the high beta and in lower
frequency ranges reflects the degree of synchronization
between column within a cortical area (von Stein et al.
1995). Furthermore coherence, the normalized crosspower
between two cortical signals, gives us the possibility to
determine synchronization between different cortical areas.
These interareal synchronizations are of specific importance
for higher cortical processes where neuronal ensembles are
thought to extend over large distances. I will present data
on local and interareal synchronization during auditory and
visual perception and during several higher cognitive tasks.
We present stimuli lasting for 1-2 s and measure the
averaged power/ crosspower spectra over 30-50 trials. We
find significant task-specific increases of coherence
between visual cortex and associative cortex during visual
perception, between several sites in parietal cortex of both
hemispheres during spatial imagery tasks, between temporal
and parietal cortex during feature integration, and more.
Changes occur in single frequency ranges or in combinations
of frequency ranges. These induced interareal
synchronizations are usually reproducible within single
subjects and reveal significant consistencies for groups of
subjects. Thus, EEG coherence analysis seems to be an
adequate tool for measuring synchronization within extended
neuronal ensembles directly in humans.
EVENT-RELATED POWER SHIFTS IN THE THETA AND ALPHA BANDS
DURING ENCODING AND RETRIEVAL
Wolfgang Klimesch
University of Salzburg, Austria
The results of two memory experiments are reported which
indicate that theta synchronization (increase in event-
related band power) is associated with episodic memory
processes. In Experiment 1, a recognition task, the EEG was
recorded during the study phase in which 96 target words
were presented and during actual recognition. The results
indicate that a) in the study phase those words that can
later be remembered show significantly more theta
synchronization as compared to words that cannot be
recognized later and that b) during actual recognition,
correctly recognized targets exhibit significantly more
theta synchronization as compared to distractors and not
recognized targets. For the alpha band it was found that
successful encoding is associated with desynchronization in
the lower in the upper alpha band. In order to rule out the
possibility that theta synchronization simply reflects
increased effort and/or attention that accompanies
successful encoding or retrieval, an incidental free recall
task was carried in Experiment 2. In the study phase,
subjects categorized the target words of Experiment 1. Then,
without prior warning subjects had to free recall the words.
As in Experiment 1, those words that were remembered later
showed significantly stronger synchronization in the theta
band. In the alpha band, no significant differences between
remembered and not remembered words were observed. The
findings are discussed with respect to a possible
involvement of hippocampal theta, induced in the cortex via
hippocampo-cortical feedback loops.
Symposium 6
Dysregulated social behavior during development:
Multiple
meanings, biological correlates, and
psychopathological outcomes
Chairs: Nathan A. Fox and Louis A. Schmidt
Participants: Susan D. Calkins, Louis A. Schmidt, Theodore
P. Zahn, Adrian Raine
Dysregulated social behavior has multiple meanings and is
associated with different psychopathological outcomes during
development. The four papers presented in this symposium
will examine the multiple biological contributions and
developmental course of different types of dysregulated
social behavior in normal as well as atypical development.
This symposium will integrate knowledge derived from several
different psychophysiological approaches and developmental
time periods. The symposium will address the following
issues: (1) multiple meanings, assessment, and origins of
dysregulated social behavior during development, (2)
multiple psychophysiological correlates, (3) behavioral as
well as psychopathological outcomes, and (4) protective
factors. Susan Calkins presents data on the relation
between cardiac vagal tone and temperament in toddlers. She
examines cardiac vagal tone indices of behavioral reactivity
and regulation and their relation to normal social
development in children. Louis Schmidt and Nathan Fox
discuss the role of frontal cortex in the dysregulation of
emotion in children. They report on the contribution of
frontal EEG activation to maladaptive social behavior in
toddlers, preschoolers, and seven year-olds. Theodore Zahn
examines the autonomic correlates of diagnosis and symptoms
in childhood psychopathology. He reports on autonomic
activity in children diagnosed with behavioral problems and
other dysregulated behaviors. Adrian Raine and Peter
Venables present longitudinal data on autonomic markers and
protective factors associated with antisocial behavior in
young adults. They examine the role of high autonomic
arousal and information-processing as possible buffers to
subsequent criminality. Nathan Fox will serve as the
discussant and provides perspective on the biological
contributions and the course of maladaptive social behavior
during development.
CARDIAC CORRELATES OF BEHAVIORAL REACTIVITY AND REGULATION
IN YOUNG CHILDREN: RELATIONS TO EARLY SOCIAL COMPETENCE.
Susan D. Calkins
University of North Carolina at Greensboro
Vagal tone and dynamic changes in Vna (vagal suppression)
may be physiological indicators or markers of both emotional
reactivity and regulation, and thus may play a role in the
development of particular social behaviors and behavior
problems. However, the relation between vagal suppression
and social outcomes may be mediated by behavioral strategies
such as self-comforting, help-seeking, and distraction that
assist the child in managing emotional responses. This
investigation examined the relations among (1) physiological
reactivity and regulation (2) emotional reactivity and
regulation and (3) social behavior in a sample of 44 two-
and three-year-old children. Children were observed
individually across tasks designed to elicit emotionality
and emotion regulation. Baseline and task measures of vagal
tone were computed during these assessments. Children were
also observed in naturalistic play with peers several times
over the course of one month. Of interest were the
relations between individual task behaviors and social,
aggressive, and solitary play behaviors with peers. The
data indicate that baseline measures of vagal tone and the
ability to suppress vagal tone during tasks were
differentially related to emotional reactivity and emotional
regulation. And, children who displayed adaptive emotion
regulating strategies and displayed an underlying pattern of
appropriate physiological reactivity and regulation were
less likely to display problematic social behavior problems
such as aggression and withdrawal. These findings will be
discussed in terms of the adaptive value of physiological
regulation in the development of self-regulatory behaviors
that may be critical to social development.
FRONTAL EEG CORRELATES OF DYSREGULATED SOCIAL BEHAVIOR IN
CHILDREN.
Louis A. Schmidt and Nathan A. Fox
University of Maryland
Recent studies have shown that right frontal EEG activation
is associated with social withdrawal as well as aggression
in children. In the present paper, we compare data from
three separate studies of toddlers, preschoolers, and seven
year-olds on (1) measures of frontal EEG asymmetry, (2)
social behaviors involving peers, and (3) behavioral
outcomes. In Study 1, baseline EEG was measured in a group
of toddlers, some of whom displayed a high proportion of
externalizing problems. This group was characterized by a
pattern of greater relative right frontal EEG asymmetry and
lower global EEG activation compared with controls. In Study
2, baseline EEG was measured in a group of preschoolers,
some of whom displayed a high proportion of shyness and
sociability during peer play. Children who were right
frontal and shy were at risk for internalizing problems,
while children who were right frontal and highly exuberant
were at risk for externalizing problems. In Study 3, EEG
was measured during a task designed to induce social anxiety
in a group of seven year-olds. Children who were classified
as socially anxious displayed a shift towards right frontal
EEG asymmetry and an increase in right frontal EEG
activation during the task in response to challenge.
Collectively, these data suggest that right frontal EEG
activation asymmetry may be a biological marker of emotion
dysregulation and maladaptive social behavioral profiles
during the first seven years of life.
AUTONOMIC CORRELATES OF DIAGNOSIS AND SYMPTOMS IN CHILDHOOD
PSYCHOPATHOLOGY.
Theodore P. Zahn
National Institute of Mental Health
Data from studies of children and adolescents with
Disruptive Behavior Disorders, Obsessive Compulsive
Disorder, and Childhood-Onset Schizophrenia will be compared
in an attempt to discern autonomic correlates of different
types of abnormal psychological functioning. In all
studies, skin conductance (SC) and heart rate (HR) were
recorded during a rest period, an orienting response
paradigm, and a simple reaction time task. In addition to
comparisons with appropriate normal control groups,
correlations of selected autonomic variables with target
symptoms were computed. Disruptive subjects had normal SC
base levels but attenuated tonic responses to the task.
Those without a subdiagnosis of conduct disorder had higher
HR than controls. Autonomic base levels were positively
correlated with impulsivity and significantly correlated
with aggression, but the direction depended on the
aggression measure. Obsessive patients did not differ
autonomically from controls, but SC activity correlated
positively with severity of obsessive-compulsive symptoms.
Schizophrenia patients showed high resting autonomic
activity and were greatly impaired on phasic and tonic
responses throughout the protocol. A failure of orienting
was associated with negative symptoms and total symptoms
while high resting spontaneous SC activity was associated
with positive symptoms. In general, the data indicate that
high levels of autonomic activity are associated with
behavior control problems -- impulsivity, some types of
aggression, obsessions, compulsions, and positive symptoms
of schizophrenia -- whereas low reactivity is associated
with impaired effortful information processing and social
withdrawal.
HIGH AUTONOMIC AROUSAL AND INFORMATION-PROCESSING AT AGE 15
YEARS AS PROTECTIVE FACTORS AGAINST CRIME AT AGE 29 YEARS.
Adrian Raine1 and Peter H. Venables2
1University of Southern California; 2York University,
England
Nothing is known about biological factors that protect a
predisposed individual from becoming a criminal. This 14-
year prospective study tested the hypothesis that antisocial
adolescents who desist from crime by age 29 years have
greater autonomic arousal and information-process than
antisocial adolescents who do become adult criminals. Skin
conductance and heart rate measures were taken at age 15
years in 101 unselected schoolboys. Of these, 17 antisocial
adolescents who desisted from adult crime (Desistors) were
matched on adolescent antisocial behavior and demographic
variables with 17 antisocial adolescents who became criminal
by age 29 (Criminals), and 17 nonantisocial, noncriminal
normal subjects (Non-Antisocials). Desistors had
significantly higher resting heart rate, resting skin
conductance activity, and skin conductance conditioning, and
faster skin conductance half-recovery times relative to
criminals. They also showed higher arousal and conditioning
relative to Non-Antisocials. These initial findings
indicate that better autonomic arousal and information-
processing may serve as factors that protect an otherwise
predisposed individual from becoming criminal.
FRIDAY AFTERNOON
Symposium 7
Brain potentials and memory: Recent developments
Chair: Michael D. Rugg
Participants: Ray Johnson Jr., Frank Roesler, Ken Paller,
Michael D. Rugg
Discussant: Cyma Van Petten
Event-related brain potentials (ERPs) are increasingly
finding favor as a means of studying human memory, and ERP
studies have begun to address important issues in several
domains of memory research. The aim of the symposium is to
illustrate the diversity of topics in human memory to which
ERPs are presently being applied, and to show how recent
findings from ERP studies add to knowledge about both the
functional architecture and the neural basis of memory
processes. Each presentations focuses on a differenthem they
cover working memory, mechanisms of retrieval from long-term
memory, dissociations between explicit and implicit memory,
and the component processes underlying recognition memory.
Common themes arising from these presentations, and
important questions for future research, will be highlighted
by the discussant.
Working Memory: An event-related brain potential analysis
Ray Johnson, Jr.1 and Daniel S. Ruchkin2
1Queens College, 2University of Maryland
Ideas about the nature of short-term memory processes have
undergone substantial change in the past two decades. The
old view of short-term memory as a unitary store has been
reconceptualized as a system consisting of three major
components: 1) an articulatory loop for verbal material, 2)
a visuo-spatial sketchpad for rehearsing visual material,
and 3) a central executive which exerts control over the
other two systems (Baddeley, 1986). Since parts of this
model remain under-specified and little is known about the
timing of short-term storage operations, we conducted a
series of ERP studies of working memory (Ruchkin et al.,
1990, 1992, 1994,1995, submitted). These ERP studies have
demonstrated the anatomical separation of different working
memory stores in normal humans. Retention of visuo-spatial
information elicited negative slow wave activity that was
largest over right central/parietal scalp whereas retention
of phonological information elicited long-lasting negative
slow wave activity that was maximal over left frontal scalp.
For both types of stimuli, the amplitude of the retention-
related slow waves increased with the amount of information
held in working memory. The topography of slow wave activity
that occurred during retention of visuo-spatial information
further demonstrated that the visuo-spatial sketchpad
consists of separate object and spatial stores. The
implications of these and other findings for models of
working memory will be discussed.
Evidence for memory traces in slow cortical brain activity
Frank Rosler, Martin Heil and Erwin Hennighausen
Philipps-University Marburg
Theories on the architecture of the human memory system
agree on the assumption that the engram is stored as a set
of synaptic changes in neocortical tissue. These changes are
assumed to take place in those brain areas in which the
information is initially processed. Retrieval of
representations is understood as a recreation of the very
same activation patterns which prevail during initial
processing. This implies (1) that the same cortical modules
should be activated during both storage and retrieval, and
(2) that representations of different quality should be
reactivated in distinct cortical areas.
We studied these hypotheses by means of slow event-
related brainpotentials. The main findings are: (1)
Retrieving associations from long-term memory is accompanied
by a slow negative shift of 5 - 10microV which prevails
about as long as the retrieval process lasts, i.e. in our
experiments, for a period of several seconds. (2) When
different types of representations have to be reactivated
the slow negative wave shows a clearly distinct topography.
Retrieval of different types of representations have to be
reactivated the slow negative wave shows a clearly distinct
topography. Retrieval of verbal, spatial, and color
representations goes together with negative slow waves over
left-frontal, parietal and occipital areas, respectively.
(3) The amplitude of the topographic maximum increases with
the number of representations which have to be reactivated.
(4) The very same topographic pattern of slow waves is
recorded during anticipation learning (primary storage of an
engram) and cued recall (retrieval of well established
representations). These findings are compatible with the
idea that memory retrieval implies a reactivation of those
cortical cell assemblies in the cortex in which the
constituting features of a mnestic entity had originally
been processed.
Memory dissociations and associated brain potentials
Ken A. Paller
Northwestern University
Neuropsychological studies of amnesic patients have shown
that certain types of memory are dependent on processing
carried out in a set of brain areas that includes medial
temporal and midline diencephalic regions, whereas other
types of memory do not require this processing. One way to
describe these results is in terms of a distinction between
"declarative" and "nondeclarative" memory. Performance
dissociations in normal subjects also lend support to this
distinction. For example, the extent of semantic processing
at encoding tends to have large effects on recognition but
not on various sorts of priming. On the other hand, certain
perceptual manipulations have larger influences on priming
than on recognition. Evidence from event-related potentials
(ERPs) has confirmed that, at the time of retrieval,
different neural processing occurs during recognition and
priming. Encoding manipulations that primarily affect
recognition are associated with ERP effects that can be
interpreted as correlates of recollection. Encoding
manipulations that primarily affect priming are associated
with ERP effects that can be interpreted as correlates of
priming. Differences between ERP correlates of recollection
and ERP correlates of priming attest to the distinction and
can be mapped on to the distinctive neural events underlying
recollection and priming as also studied with other
techniques.
MEMORY WITH AND WITHOUT RETRIEVAL OF CONTEXT: STUDIES WITH
EVENT-RELATED POTENTIALS
Michael D. Rugg
University of St Andrews
The distinction between recognition memory judgments that
are accompanied or unaccompanied by retrieval of the study
context is central to so-called 'dual-process' models of
recognition memory. According to these models, recognition
memory can be based on two independent kinds of information:
recollection - the successful retrieval of the original
study episode (recollection); and familiarity - the feeling
that a test item has been experienced recently in the
absence of explicit memory of the study episode. A critical
distinction between these two forms of recognition memory is
that only recollection is associated with the retrieval of
information about study context; recognition based on
familiarity is acontextual. Thus the two kinds of
recognition memory can be dissociated by segregating
accurate recognition memory judgments according to whether
the recognised items can be correctly assigned to their
study context. This procedure was employed to study the ERP
correlates of recognition memory based on recollection and
familiarity. Two components, one with a left parietal
distribution, and the other maximal over the right frontal
scalp, differentiated ERPs elicited by recollected' and
'unrecollected' items, demonstrating that ERPs are sensitive
to the processes supporting memory for context (source).
Subsequent studies demonstrated that the two components
index dissociable processes, hypothesised to be associated
with the retrieval of information from episodic memory, and
the 'post-retrieval' processing of such information,
respectively. No consistent evidence has yet been found of
an ERP signature of recognition based upon familiarity; the
implications of this negative finding for dual-process
models will be discussed.
Symposium 8
The construction of social reality in the
psychophysiological laboratory
Chair: William Gerin
Participants: Wolfgang Linden, Kevin Larkin, Nicko
Christenfeld, Timothy W. Smith,
Discussant: Douglas Carroll
A recent trend in cardiovascular reactivity testing concerns
the use of stressors which involve social interactions. It
seems likely that much of the stress we face in daily life
comes from the social environment; thus, valid
representations of social interaction may provide new
insight into the manner in which stress produces
physiological effects which may have long-term health
consequences. However, the development of social interaction
paradigms is difficult, since we are attempting to create a
sitaution that engages the subject, and causes her/him to
behave as though the situation were occurring outside the
laboratory. The panel will deal with some of the more
important issues that must be considered in these sorts of
studies. Wolfgang Linden discusses gender differences in
response to an anger-provocation task, and shows that in
order to elicit reliable responses from female subjects, the
provocation must be severe, in contrast to males. Kevin
Larkin describes social confrontation procedures that may
provide an ecologically valid means of eliciting
cardiovascular responses in the laboratory; this work is
concerned equally with the affective/cognitive, as well as
physiological, responses. Nicko Christenfeld discusses the
role of task engagement as it may affect active coping, and
its interaction with the social context provided. Finally,
Tim Smith describes his work on the interpersonal circumplex
as a means of understanding social motivation in
interactions between married couples. Doug Carroll will
provide an integrative discussion of the factors one must
consider in attempting to create an ecologically valid
social interaction in the laboratory.
GENDER DIFFERENCES AND SUBTLE PROTOCOL DIFFERENCES AFFECT
THE REPLICABILITY OF ANGER-PROVOCATIONS
Wolfgang Linden, Thomas Rutledge, and Tracey Earle
University of British Columbia
Review of the literature suggests that anger provocations in
the lab trigger large and reliable cardiovascular responses
that exceed those observed under less challenging
conditions. We have now had an opportunity to apply anger
provocations in three different studies and observed less-
than-perfect replicability of effects. In Study 1, blood
pressure and heart rate (BP, HR) changes were twice as large
as noted in comparable active coping challenges without
anger provocation. Men showed greater responses than women.
In Study 2, the gender difference was replicated. Anger
provocation in addition to arithmetic triggered larger
responses than were apparent during arithmetic alone, but
that was not true for diastolic BP or for cortisol responses
in women. In Study 3, with a women-only sample, an attempt
at anger provocation superimposed on a 3-task protocol was
completely ineffective for augmenting BP and HR responses.
In comparing results from these three studies, it becomes
clear that anger provocation effects are difficult to find
in samples of women, require fairly nasty interruption
statements, and are more likely replicable when the tasks
involve vocal speech.
CARDIOVASCULAR AND BEHAVIORAL RESPONSE TO SOCIAL
CONFRONTATION: MEASURING REAL-LIFE STRESS IN THE LABORATORY
Kevin T. Larkin, Nicole Frazer, Elizabeth Semenchuk, and
Sonia Suchday
West Virginia University
One of the major criticisms confronting investigators of
cardiovascular responding to stress is the relative lack of
ecologically-valid strategies for eliciting heart rate and
blood pressure reactions. The purpose of the three studies
presented in this paper is to describe the development and
validation of a laboratory social confrontation procedure
designed to measure not only cardiovascular responses, but
concomitant behavioral and self-reported affective/cognitive
responses. From a list of 30 potential laboratory conflict
situations, two were selected based upon ratings of ecologic
validity obtained from 40 undergraduate students: a scene
where a participant is requested to confront a noisy
neighbor, and another where a participant is requested to
confront a messy roommate. In the first study, students
with a parental history of hypertension evidenced
significantly greater SBP and more negative confrontive
behaviors during both scenes. In the second study,
instructions for the laboratory task were varied so that
participants were instructed to express their anger freely
during one scene and suppress their anger during the other.
Behavioral, affective, cognitive, and DBP responses were
elevated during anger expression in contrast to anger
suppression. In the third study, students from families
differing in levels of cohesion and adaptability showed
differences on cardiovascular and behavioral measures during
the social confrontation procedure. Based upon these initial
investigations, we have found that the social confrontation
challenge provides a reliable method for assessing response
parameters concurrent to cardiovascular responding, as well
as measuring more representative real life tasks without
losing the standardization the laboratory provides.
THE SOCIAL AND SITUATIONAL CONTROL OF TASK ENGAGEMENT AND
CARDIOVASCULAR REACTIVITY
Nicholas Christenfeld1, Laura Glynn1, James Kulik1, and
William Gerin2
1University of California-San Diego, 2Cornell University
Studies of cardiovascular reactivity generally compare the
level of a physiological variable, such as blood pressure,
during a task to the resting level. The difference is
interpreted as reflecting the effect of that task. However,
such changes may reflect the extent to which the subject is
engaged in the task as much as the nature of the task
itself. In the present study we examine two variables that
might influence task engagement. Subjects performed a word
search task while blood pressure and heart rate were
continuously monitored. Half received performance norms and
half received no information on how many words could be
found. Subjects provided with norms showed significantly
greater systolic blood pressure (SBP) increases during the
task (10.9 vs. 5.4 mmHg). The second manipulation explored
whether the same difference could be created by simply
altering the experimenter's behavior. For half the
subjects, the experimenter provided encouragement (though no
performance feedback), and for half the experimenter did not
provide encouragement. The encouraged subjects showed a
significantly greater increase in SBP (10.5 vs. 5.6 mmHg).
Encouraged subjects also indicated that they felt greater
control over the outcome. The results indicate that the way
the task is approached, not just the nature of the task,
determines physiological responses. They also indicate that
positive regard from an experimenter does not always produce
decreased reactivity (the social support effect), but may
increase arousal by increasing the effort put into the task.
Increased reactivity is not necessarily a marker of stress,
but can also indicate enjoyable active coping.
AGENCY, COMMUNION, AND CARDIOVASCULAR REACTIVITY DURING
MARITAL INTERACTION.
Timothy W. Smith and Linda C. Gallo
University of Utah
The interpersonal circumplex is a useful conceptual and
methodological tool in studies of social determinants of
cardiovascular reactivity. Two broad classes of such
influences are motives involving agency (i.e., competition,
dominance, achievement) and communion (i.e., relatedness,
conflict). To evaluate the effects of these social
motivations on cardiovascular reactivity during marital
interaction, 60 married couples participated in a current
events discussion task. In a factorial design, half of the
couples were told that their verbal intelligence would be
evaluated (vs simple clarity of speech) and half were
assigned to opposite sides of the topic to be discussed (vs.
the same side). Responses to Wiggins' Interpersonal
Adjective Checklist indicated that disagreement led wives to
view their husbands as more hostile and less friendly, but
did not alter husbands' descriptions of their wives'
behavior during the task. Evaluative threat led husbands to
rate their wives as more dominant and less submissive, but
did not alter wives' ratings of their husbands. Evaluative
threat(but not disagreement) increased systolic, diastolic
and heart rate responses of husbands, but not wives.
Disagreement (but not evaluative threat) increased systolic,
diastolic, and heart rate responses of wives, but not
husbands. Thus, the interpersonal circumplex provided a
dimensional conceptualization of sex differences in
reactivity in this context, as well as a sensitive
assessment of the corresponding interpersonal appraisals.
SATURDAY MORNING
Symposium 9
GO-NOGO: Cerebral inhibitive control mechanisms and
behavior.
Chair: C.H.M.Brunia
Participants: J. Richard Jennings, G.J.M. van Boxtel,
Martin Eimer, C.H.M. Brunia
In recent theories about attention its intimate relation to
action is stressed. Both attention and action are based upon
inhibitory mechanisms, by which selection in the input and
the output channels of the brain is possible. The first
contribution is theoretical: it applies the selection for
action view upon psycho-physiological results obtained
during the foreperiod of reaction time tasks. In the next
two contributions electrophysiological responses obtained in
a number of experiments will be interpreted in terms of
patterns in inhibition and excitation. In the fourth
contribution the possible neuro-anatomical pathways
underlying inhibition in attention and action will be
described. The aim of this symposium is to attempt to find a
common framework in which behavioral, psychophysiological
and neuroanatomical data concerning response activation and
inhibition can be put together.
ATTENTION AS COORDINATION FOR ACTION-INHIBITION DURING
PREPARATION AND PROGRAMMING AS AN EXPLANATION FOR AUTONOMIC
AND CORTICAL CHANGES.
J. Richard Jennings1 and Maurits W. van der Molen2
1University of Pittsburgh, 2University of Amsterdam
As argued by Neumann, Allport, and others, both perceptual
and motoric selection may arise from the requirements of
action. Physical actions must be coordinated not only
between motor effectors, but also with perceptions of the
environment and physiological state. This view provides an
alternative to resource theories of attention. Further,
coordination for action implies the psychophysiological
changes occurring during preparation. Preparation is
examined in warned reaction time paradigms by varying the
timing and predictability of and information about the
anticipated stimulus and the response required. Preparation
necessarily implies a cost. Other actions--including the
maintenance and formation of perceptions linked to action--
must be inhibited to permit the programming and execution of
the anticipated action. Preparation time can be minimized
and efficient with information about the timing and nature
of the anticipated response. An assessment of the precision
of the anticipated perception-action linkage and how it
interacts with competing perception-action linkages will
predict physiological changes occurring in the preparatory
period. Results with heart rate and anticipatory cortical
potentials can be considered with the assumption that
transient heart rate change is one aspect of the
coordination of response initiation and regional cortical
changes interpreted as facilitation and/or inhibition of
different perceptual-motor linkages. This analysis is most
compelling when performance at a fixed instant requires that
motor programming deal solely with the anticipated action,
inducing a blocking of interfering actions. Coordination
for action will be illustrated during both mnemonic
retrieval and during selection of a simple motor response.
EVENT-RELATED POTENTIALS AND HEART RATE IN A STOP-SIGNAL
TASK
G.J.M. van Boxtel1,2, W.P.M. van den Wildenberg1, M.W. van
der Molen2, J.R. Jennings3, and C.H.M. Brunia1
1Tilburg University, 2University of Amsterdam, 3University
of Pittsburgh
Event-related brain potentials (ERPs) from 28 mostly
anterior electrode positions, heart rate, respiration,
agonist and antagonist EMG, and continuous force output were
recorded in a stop-signal task. The respond stimulus was an
arrow pointing left or right. On 70% of the trials, it was
colored green and the subjects had to make a response with
the left or the right index finger (GO trials). On 10% of
the trials, it was colored red, and no response was to
follow (NOGO trials). On 20% of the trials, the arrow was
green, but after a variable interval it briefly turned red,
upon which the subjects had to inhibit their response (STOP
trials). The latency of the STOP signal was chosen so that
the subjects could inhibit their response on half of the
trials. The behavioral results fitted into a horse race
model, in which independent activation and inhibition
processes race for completion. Response inhibition was
accompanied by heartbeat slowing, which was largest when the
stimulus was presented late in the cardiac cycle. The ERPs
were characterized by a small transient (pre)frontal
negativity followed by a large broad central positivity.
Both components were larger on inhibition trials than in
response trials. The first negative component was much
smaller or absent in STOP trials than in NOGO trials.
Results are discussed in terms of current behavioral and
neurophysiological theories of inhibitory control.
SELECTION AND INHIBITION IN ATTENTION AND MOTOR ACTIVATION
Martin Eimer
University of Munich
Processes of selective attention have recently been
characterized in terms of selection-for-action, thus
suggesting a close relationship between attentional
mechanisms and motor preparation and activation processes.
Electrophysiological correlates of perceptual and motor
selectivity will be discussed, focussing mainly on ERP
indicators of attentional and motor inhibition processes.
Three areas of research will be reviewed: (1) Studies
investigating the time course and distribution of ERP
effects related to attention and motor inhibition elicited
by single visual and auditory stimuli in a precueing
paradigm; (2) Studies investigating mechanisms of selecting
response-relevant information (or supressing irrelevant
information) in visual search tasks; (3) Studies
investigating the inhibition of response tendencies that are
elicited by masked non-targets with the help of the
Lateralized Readiness Potential (LRP).
NEURO-ANATOMICAL PATHWAYS INVOLVED IN GO-NOGO ACTIVITY
C.H.M.Brunia
Tilburg University
Order in our behavior is based upon spatiotemporal selective
processes that take place both in the input channels and in
the output channels. In order to understand behavior it is
necessary to understand how selection takes place and where.
It is a common notion that the sensory cortex is a target
for afferent volleys, informing the brain about both the
outside world and our body, while the motor cortex is
considered a starting point for efferent volleys, that via
the motoneurons give rise to muscle contractions to react or
act in the outside world. However, just as the sensory
cortex, the motor cortex needs to be informed via
subcortical pathways before the efferent stream of
information actually can give rise to any change in our
behavior. The thalamus is a crucial relay center for sensory
information from different modalities to separated cortical
areas, known as the primary projection areas. The motor
nuclei in the thalamus are also part of separated thalamo-
cortical systems. Input from all cortical areas is sent to
the neostriatum, via which these separate systems
areactivated. It is hypothesized that comparable control
mechanisms from the prefrontal cortex are active in the
patterning of inhibition in the anticipation of attention
and action. We will try to interpret the results of the
first three papers in terms of the (expanded) model,
presented at the San Diego meeting.
Symposium 10
The Psychophysiology of Fatigue
Chairs: Evan A. Byrne and Wolfram Boucsein
Participants: Akihiro Yagi, June J. Skelly, James C.
Miller, Mark R. Rosekind
Discussant: John A. Stern
The problem of fatigue is becoming increasingly recognized
as an important safety concern in many human endeavors
ranging from workplace safety to commercial transport. In
laboratory research fatigue is an established construct in
theories of attention and vigilance. Fatigue is a dominant
research area for many applied psychophysiologists and
crosses the domains of human factors and ergonomics,
transportation and health, and basic attention processes.
Each paper in this symposium addresses the role of
psychophysiological methods as an approach to understand
fatigue. Using distinct methodology the speakers in this
symposium will demonstrate the role of psychophysiology in
the study and detection of fatigue in laboratory and applied
settings. Yagi presents data on task enjoyment and fatigue
using a new measure based on cortical potentials associated
with eye movements. Skelly will present data on the use of
EOG-based measures to index the magnitude of attention in
sustained task performance. Miller will present EEG data
collected on long-haul truck drivers using a unique
methodological approach to detect periods of fatigue.
Finally, Rosekind will describe the use of physiological
measures, including EEG, EOG, EMG, & HR, in the study of
fatigue in aviation environments as part of the NASA Ames
Fatigue Countermeasures Program. These presentations
capture the breadth of research questions, methodology, and
environments encountered by psychophysiologists interested
in fatigue.
VARIATIONS OF EYE FIXATION RELATED POTENTIALS IN VISUAL
TASKS
Akihiro Yagi
Kawnsei Gakuin University
Application of ERP is difficult in ergonomics because of
eye-movement artifacts. When a subject observes something,
the eye movement record shows a step-like pattern consisting
of saccades and eye fixations. We can obtain a specific ERP
called the eye fixation related potential (EFRP) with
averaging EEG time-locked to onset of eye fixations (i.e.
offset of saccades). Two experiments were conducted
evaluating the EFRP as a potential index of fatigue. In the
first experiment, 10 subjects performed figure drawing tasks
on positive (white) and negative (black) screens for 40 min
while EFRP was measured. EFRP differences were evident
between the positive and negative screens. A small
decrement in the EFRP with time on task was observed in some
subjects. All subjects enjoyed the task. In the second
experiment, 13 subjects performed VDT tasks during a 1.5
hour task period. Tasks included a free search task and two
kinds of computer games. EFRP was obtained during the task
period and during rest conditions immediately pre- and post-
task. EFRP latency decreased slightly during the free
search task for 15 min. Subjects enjoyed the VDT tasks and
games and few reports of fatigue symptoms occurred during
these conditions and EFRP shows few changes. However,
fatigue symptoms increased post-task and post-task EFRP
latency was significantly delayed compared to latencies
obtained pre-task. The EFRP may be applicable as an index
of fatigue in long lasting tasks.
EOG INDICES OF ATTENTIONAL FLEXIBILITY: DESIGNING TEMPORAL
INTERFACES TO MANIPULATE THE CAPTURE AND ENTRAINMENT OF
ATTENTION
June J. Skelly
Wright-Patterson AFB, OH
A series of studies investigated the effects of portraying
temporally patterned information on subjects' ability to:
(1) maintain a state of sustained attention over time; (2)
switch attention among different streams of sequential
information. Subjects engaged in a simple decision making
task where task relevant information was variably mapped
across different temporally patterned sequential information
streams. Subjects participated in three studies over a 3
month period and performed the task over 4 consecutive days
in each study. Subjects monitored two co-occurring,
temporally patterned information sources for target
information for 2.5 hours in each daily session. Results
indicated that: (1) response times and EOG measures were
differentially affected by temporal patterns associated with
both relevant and irrelevant information sequences; (2)
residual effects on attentional flexibility, due to exposure
to certain timing patterns, were evident across days within
a study, and across studies separated by at least one month;
(3) temporal pattern complexity appeared to affect a
subject's attentional state and ability to maintain a high
level of attention. A later study attempted to design a
Temporal Interface for an F-16 cockpit display to evaluate
temporally patterned sequential information in a real world
setting. Using temporal structures from earlier studies,
but with rates increased tenfold, a warning cue was
periodically presented on a modified Radar Warning Receiver.
Pilots had to initiate countermeasures when they detected
the signal. Results indicated attention was captured by
certain timing patterns of information. These studies
suggest ways to exploit and energize an operator's
attentional mechanism in either a slow vigilance task
setting, or a rapidly changing, dynamically complex work
environment.
DESCRIPTIVE QUANTITATIVE ANALYSIS OF 4,000 HOURS OF DAY AND
NIGHT EEG RECORDED FROM TRUCK DRIVERS ON THE
OPEN-HIGHWAY
James C. Miller
Miller Ergonomics and The Scripps Research Institute
The data came from 320 round-trips contributed by 80
commercial drivers (4 or 5 trips each) driving both day and
night revenue cargo runs of 10 or 13 hours each. The sleep
and driving EEG data were collected with Medilog recorders
at 128 samples/sec. Non-artifactual data collected when the
truck was moving faster than 45 mph were reduced through
Fourier transform to compressed band arrays for 20-sec
epochs, with associated manual scoring to identify
artifactual and drowsy epochs. Each 20-second-epoch was
represented by the mean of five 4-second epochs. The
arcsines of relative amplitude estimate within each band of
interest (theta, TH; alpha, AL) were used, and were
standardized with reference to the relative spectral
amplitude of arcsine relative beta (BE). A within-subject
z-score was based upon the mean and standard deviation of
the first 100 useable 20-second epochs that occurred when
the truck was traveling greater than 45 mph during the
drivers first trip of the week. The z-scores were averaged
into sequential, 1-minute z-scores. The means and the
rectilinear regression slopes for the standard scores of
TH/BE and AL/BE were used to estimate EEG values at the
beginning and end of each outbound and inbound leg of each
trip for each driver. One-week-long time series plots of
TH/BE and AL/BE were prepared, showing the slopes and
intercepts of each leg of each trip. The time series showed
evidence of acute fatigue and cumulative fatigue, and
circadian and semi-circadian patterns of drowsiness.
Evaluating fatigue in operational settings: The NASA Ames
Fatigue Countermeasures Program
Mark R. Rosekind1, Kevin Gregory2, Donna Miller2, Lissa
Webbon2, and Ray Oyung3
1NASA Ames Research Center, 2Sterling Software,3San Jose
State University
n response to a 1980 Congressional request, NASAAmes
initiated a program to examine fatigue in flight
operations.The Program objectives are to examine fatigue,
sleep loss, andcircadian disruption in flight operations,
determine the effectsof these factors on flight crew
performance, and the developmentof fatigue countermeasures.
The NASA Ames FatigueCountermeasures Program conducts
controlled laboratoryexperiments, full-mission flight
simulations, and field studies.A range of subjective,
behavioral, performance, physiological,and environmental
measures are used depending on studyobjectives. The Program
has developed substantial expertise ingathering data during
actual flight operations and in other worksettings. This
has required the development of ambulatory andother measures
that can be carried throughout the world and usedat 41,000'
in aircraft cockpits. The NASA Ames FatigueCountermeasures
Program has examined fatigue in shorthaul,longhaul,
overnight cargo, and helicopter operations. A recentstudy
of planned cockpit rest periods demonstrated
theeffectiveness of a brief inflight nap to improve
pilotperformance and alertness. This study involved
inflight reactiontime/vigilance performance testing and
EEG/EOG measures ofphysiological alertness. The NASA Ames
Fatigue CountermeasuresProgram has applied scientific
findings to the development ofeducation and training
materials on fatigue countermeasures,input to federal
regulatory activities on pilot flight, duty, andrest
requirements, and support of National Transportation
SafetyBoard accident investigations. Current activities are
examiningfatigue in nonaugmented longhaul flights,
regional/commuterflight operations, corporate/business
aviation, andpsychophysiological variables related to
performance.
SATURDAY AFTERNOON
Symposium 11
Electrophysiologic studies of depression and
anxiety: New findings and theoretical synthesis
Chairs: Gerard E. Bruder and Richard J. Davidson
Participants: Richard J. Davidson, Wendy Heller, Gerard
Bruder, Bruce Cuthbert
Discussant: David Watson
There is considerable comorbidity of depressive and anxiety
disorders, and self-ratings of depression and anxiety are
highly correlated. The extent to which depressive and
anxiety disorders have a common or different pathophysiology
is an important issue addressed in this symposium. Recent
efforts have been directed at developing psychometric scales
that can distinguish symptom subtypes of depression and
anxiety. Relatively little attention has, however, been paid
to assessing the differential effects of depressive and
anxiety symptoms in electrophysiologic and neuroimaging
studies. There is evidence that depression and anxiety have
different effects on regional hemispheric activity, which
could explain some conflicting findings in anxiety have
different effects on regional hemispheric activity, which
could explain some conflicting findings in this area. The
presentations in this symposium review new findings from
electrophysiologic and imaging studies that evaluate the
effects of comorbidity, diagnostic subtype, and specific
symptoms of depression and anxiety on a variety of measures,
including quantitative EEG, PET scans, event-related brain
potentials, startle responses, autonomic responses, and
neuropsychologic tests. Theoretical formulations are also
presented for integrating these findings. The presentations
will be discussed in relation to the "tripartite model" of
anxiety and depression (Clark &Watson, 1991, J. Abnorm.
Psychol., 316-336).
CORTICAL AND SUBCORTICAL CONTRIBUTIONS TO POSITIVE AND
NEGATIVE AFFECT: DISTINGUISHING DEPRESSION FROM ANXIETY
Richard J. Davidson
University of Wisconsin-Madison
Depression and anxiety share certain symptoms in common and
also feature particular distinguishing symptoms. A common
observation in clinical research is the extensive co-
morbidity between depression and anxiety. These facts raise
questions about the extent to which they share certain
biological substrates in common and also whether the current
diagnostic categories adequately capture the variance
commonly observed in nature. This talk will first present a
model based upon prior data and theory of the similarities
and differences in the cortical and subcortical substrates
of anxiety and depression, focusing on prefrontal and
parietal cortex and the amygdala. Data from several
electrophysiological and neuroimaging studies on cortical
asymmetries and amygdala activation in both depressed and
anxious subjects will be presented. Different patterns of
prefrontal electrophysiology characterize depressives with
or without certain features of anxiety. All depressives
appear to show increased metabolic activity in the amygdala
and greater metabolic activity in the amygdala is associated
with increased negative affect. Subjects with social phobia
show increased right-sided prefrontal and parietal
activation. These findings lead to the suggestion that
activation of the amygdala may be common to both depression
and anxiety, while cortical activity is likely to differ
between them. The implications of these data for parsing
mood and anxiety disorders is considered, along with
specifying the particular subcomponents of affective
processing that may be impaired in these different types of
disorders.
MAKING SENSE OF BRAIN ACTIVITY IN DEPRESSION AND ANXIETY:
THE CIRCUMPLEX MODEL OF EMOTION, SUBTYPES, AND COMORBIDITY
Wendy Heller
University of Illinois
Numerous studies have documented specific patterns of
anterior and posterior brain activity associated with
depression and anxiety. However, discrepancies, failures-to-
replicate, and opposing findings abound. In an attempt to
arrive at a better understanding of the brain mechanisms
involved, I will review this literature in light of a model
of emotion and regional brain activity which integrates
neuropsychological and psychophysiological data on
cognitive, emotional, and autonomic functioning with the
valence and arousal dimensions of the circumplex structure
of emotion. In previous work, we have related core symptoms
of depression and anxiety to the valence and arousal
dimensions of the circumplex model of emotion, and have, in
turn, linked these dimensions to specific patterns of brain
activity. Following from the theory and our previous
findings, I propose that attention be given to two crucial
issues that are too often overlooked in the relevant
literature, specifically, subtypes and comorbidity. In
particular, a review of the literature and our own empirical
findings indicate that melancholic versus non-melancholic
depression and anxious apprehension versus anxious arousal
are important subtypes of depression and anxiety that appear
to be associated with different, at times even opposing,
patterns of regional brain activity. Therefore, the
comorbidity of depression and anxiety (and their subtypes)
may substantially confound findings for a given sample. In
sum, the inconsistencies in the literature may be mitigated
by taking into account subtypes and comorbidity in future
research paradigms examining depression and anxiety.
QUANTITATIVE EEG AND EVENT-RELATED POTENTIAL (ERP) FINDINGS
IN MAJOR DEPRESSION: RELATIONS TO ANXIETY AND ANHEDONIA
Gerard Bruder, Craig Tenke, Regan Fong, Paul Leite,
James Towey, Jonathan Stewart, and Frederic Quitkin
New York State Psychiatric Institute
Recent theories and behavioral laterality findings emphasize
the importance of distinguishing effects of depression from
those of anxiety. Based on a model of asymmetric hemispheric
activity in depression and anxiety (Heller et al., 1995, J.
Abnorm. Psychol.,327-333), it was predicted that anxious and
nonanxious depressed patients would differ in EEG alpha
asymmetry at parietotemporal sites. Resting EEG (eyes closed
and open) was recorded from 44 unmedicated patients having a
unipolar major depressive disorder (19 with and 25 without
an anxiety disorder), and 26 normal controls using 30 scalp
electrodes. As predicted, depressed patients with an anxiety
disorder differed from those without an anxiety disorder in
alpha asymmetry at posterior but not at anterior sites.
Nonanxious depressed patients showed an alpha asymmetry
indicative of relatively less activation over right
parietotemporal sites, whereas anxious depressed patients
showed the opposite alpha asymmetry. In the same study, ERPs
were recorded during an oddball task with complex tones.
Normal controls and patients with low scores on a physical
anhedonia scale had greater P3 amplitude over right than
left central sites, whereas patients with high anhedonia
scores did not show this right hemisphere advantage. These
findings are consistent with a model in which anhedonic
depression is associated with right parietotemporal
hypoactivation, whereas anxious arousal is associated with
hyperactivation in this region.
Fear and anxiety: Theoretical distinction and clinical test
Bruce N. Cuthbert, Margaret M. Bradley, and Peter J. Lang
University of Florida
Clinical studies of anxiety disorder patients are described
that utilize multi-measure psychophysiological recording to
assess emotional reactivity in perception, imagination, and
action. This research presents the data from a large (n=150)
group of patients, including those with simple phobia,
social phobia, panic disorder, or post-traumatic stress
disorder (PTSD). The assessment procedure involves interview
and questionnaire measures, followed by psychophysiological
monitoring during emotional imagery and picture processing
as well as during standard physical (e.g., step test) and
psychological challenge tasks (e.g., speech performance).
In addition to dependent measures of autonomic and
respiratory activity, these studies assess affective
modulation of the probe startle reflex. The data
demonstrate significant variation among patients in the
relationships between affective judgments and autonomic and
startle responses. Panic and PTSD patients showed
significantly larger base startle responses than simple or
social phobics, whereas specific clinically-relevant fear
stimuli prompted greater startle potentiation for those
diagnosed with simple or social phobia. Marked differences
in autonomic and probe startle reflex responses were
obtained between patients showing high and low negative
affect and generalized psychopathology. This data base is
discussed in terms of how it aids in sharpening
psychophysiological distinctions between fear (i.e., phobia)
and anxiety (as in generalized anxiety disorder), as well
as how it illuminates issues regarding differential
diagnosis and the significance of depressive co-morbidity in
anxiety disorders.
DISCUSSANT
David Watson
University of Iowa
Clark and Watson (1991, J. Abnorm. Psychol., 316-336)
proposed a 'tripartite model' of depression and anxiety that
divides relevant symptoms into 3 groups: symptoms of general
distress that are largely nonspecific, manifestations of
anhedonia and low positive affect that are specific to
depression, and symptoms of somatic arousal that are
relatively unique to anxiety. The model originally was
developed from measures of self-rated symptoms. However, the
papers in this symposium will examine the differentiation
between anxiety and depression using various
psychophysiological indices. I will integrate the findings
from the individual papers and examine the extent to which
they are compatible with the general tripartite model.
Symposium 12
On becoming selective: Integrating cognitive and
electrophysiological approaches to the development
of attention
Chair: Lourdes Anllo-Vento
Participants: James T. Enns, James M. Swanson, David
Friedman, Margot J. Taylor
Researchers interested in understanding the developmental
time-course of attention have taken widely varied approaches
to the issue. Some have used development as a tool to help
test the validity of a particular model of attention. Others
have resorted to attentional theories to shed light upon
developmental disorders of attention. And still others have
employed attentional theories and psychopathology to
determine how attention develops. This symposium will
examine what can be accomplished by integrating well-known
cognitive and psychophysiological paradigms and applying
them to the study of normal and abnormal development of
attention. The first speaker will illustrate the benefits
of using well-defined behavioral tests to assess changes in
attentional capabilites over the lifespan. We shall see how
different attention tasks seem to follow distinct
developmental courses, information that might prove useful
in conceptualizing the sub-components of the attentional
system. The next speaker will illustrate how theory-driven
behavioral analyses can help establish a taxonomy of
attention deficits. The last two speakers will focus on
electrophysiological measures of auditory and visual
selective attention, respectively, and will consider the
benefits afforded by jointly probing neural and behavioral
indices of cognitive development. The aim of the symposium
is to help us establish effective experimental strategies
that incorporate the knowledge accrued from cognitive and
psychophysiological approaches to the question at hand.
THE DEVELOPMENT OF SELECTIVE ATTENTION OVER THE LIFESPAN:
BEHAVIORAL MEASURES
James T. Enns
University of British Columbia
I will highlight some of the behavioral patterns we have
seen emerge in our laboratory over the past decade or so on
research on the development of visual attention. We began
our studies of visual attention in school-age children
(e.g., Enns & Girgus, 1985; Enns & Brodeur, 1989) but in the
past few years have begun to compare these trends with those
that can be seen at the other end of life (Brodeur & Enns,
submitted; Plude, Enns & Brodeur, 1994; Trick & Enns,
submitted; Trick, Enns & Brodeur, in press). The data I
will summarize will focus on three separable methods of
attention measurement that are known to vary in childhood as
well as in old age: covert visual orienting, visual search,
and visual enumeration. In each case it will be shown that
there are differential rates of development for sub-
components of these tasks. In some cases there is almost no
measureable change across the full span of life, in other
cases there is improvement early in life but no decline in
later life, and in still other cases the oft-cited inverted-
U function is observed. These results have alternately
provoked optimistism and pessimism in us, as we have
explored the possibility of linking these behavioral changes
over the lifespan to theories of development, to theories of
attention, and to changes in the observable nervous system.
ABNORMAL DEVELOPMENT OF ATTENTION AS INDEXED BY CLINICAL,
NEUROPSYCHOLOGICAL, AND NEUROPHYSIOLOGICAL DESCRIPTIONS OF
ATTENTION DEFICIT DISORDER
James M. Swanson
University of California at Irvine
Over the past few years, a team of investigators from UC
Irvine, UCLA, and the University of Oregon has applied a
combined approach to the description and measurement of
cognitive deficits in children with attention deficit
hyperactivity disorder (ADHD). One group within this project
has focused on behavioral subtyping, a second on the
measurement of structural and functional abnormalities in
brain architecture, and a third has taken as a point of
departure the idea advanced by Posner and his colleagues
that a neuroanatomical network mediates the various aspects
of attentive behavior: alerting (right frontal), orienting
(right parietal), and executive control (anterior
cingulate). In this vein, we have recently extended our
understanding of visual-spatial orienting in ADHD children
by investigating the impact of comorbid conditions on a
child's performance on the Posner cuing task. In this task,
a "pure" ADHD subgroup showed the abnormal pattern of
reaction-time differences (RVF>LVF) when responding to
targets after 800 ms SOAs (Swanson et al.,1991), while a
"mixed" subgroup with ADHD and comorbid disorders did not
(Ottolini, 1995). This finding suggests that specific ADHD
subgroups may not have the same type of attention deficits.
We are now carrying out high density electrophysiological
recordings on neuropsychologicallly homogeneous groups of
ADHD children in order to characterize the temporal aspects
of their information processing deficits. We expect this
approach will help us understand why different attention
deficits are manifested by distinct subtypes of children
with ADHD.
THE DEVELOPMENT OF SELECTIVE ATTENTION: AN EVENT-RELATED
POTENTIAL PERSPECTIVE
David Friedman1 and Steve Berman2
1New York State Psychiatric Institute, 2UCLA
Neuropsychiatric Institute
The development of auditory selective attention was assessed
using event-related potentials (ERPs) and behavioral
measures, with children, adolescents, and young adults as
subjects. In separate blocks, subjects heard two sequences
of pure tones (low- and high-pitched) or consonant-vowel
syllables (CVs; e.g., ba vs da). Subjects were required to
attend to one of the two stimuli in order to detect a
deviant (longer-duration) target embedded within the
attended sequence, while ignoring the sequence comprised of
the other stimulus (which also contained standard and
deviant stimuli). The effect of selective attention was
operationalized using the Nd difference waveform (ERP
elicited by the unattended standard subtracted from that
elicited by the attended standard). There was an increase in
early Nd amplitude and a decrease in its latency for both
pure tones and CVs from childhood through young adulthood.
For the amplitude measure, this effect was much more marked
for CVs. The major effect of age involved reduction of
negative-going ERP amplitude elicited by stimuli in the
unattended channel, which was accompanied by an age-related
decrease in the number of behavioral responses to deviants
in the unattended channel. The age-related reduction in
negativity to stimuli in the unattended channel was
interpreted as indicating that with increasing age there is
an improvement in the narrowing of the attentional focus,
with the major change taking the form of greater facility in
rejecting stimuli in the unattended channel. The data appear
to fit Naatanen's model (1982; 1990) of selective attention
based on the processing negativity.
DEVELOPMENT OF EARLY VISUAL SELECTIVE ATTENTION PROCESSES
STUDIED WITH EVENT-RELATED BRAIN POTENTIALS
Margot J. Taylor
University of Toronto
We have investigated the development of attentional
processes in normal and clinical groups of school-aged
children. I will review three even-related potential (ERP)
studies with emphasis on the earlier components. In the
first, visual search paradigms were used to study parallel
processing of pop-out stimuli and serial processing of
feature conjunctions. Posterior P1 and N2, and anterior P2
and N2 were measured. In 7-8 yr-olds there was little effect
of task; with increasing age, the processing associated with
the colour pop-out became faster than that of the size on
serial tasks. These data suggest that developmental changes
in early stages of visual selection are continuing at this
age. Data from normal children will be compared to those
from children with attention deficit hyperactivity disorder
(ADHD). The second study assessed the effects of medication
on a continuous performance task. On medication ADHD
children showed a normalization of P3 and behavioural
measures, but increased N2 and P2 latencies, suggesting more
controlled decision processes leading to improved
behavioural scores. The third study examined patterns of
hemispheric specialization during reading tasks in 8-10 yr-
olds with very low birth weight (VLBW). While control
children showed LR at N2, VLBW
children showed only Rdergraduate
student subjects (3 male, 21 female). The 10 imagery scripts were based
on those used by Fiorito & Simons (1994, Psychophysiology,513-521) and
were designed to elicit emotions within all four quadrants of the
emotion circumplex defined by the affective dimensions of valence and
arousal. Each imagery trial consisted of a 20 second initial relaxation
period, a 30 second period during which the script was presented to the
subject, and a 30 second period during which the subject was required
to imagine the scene described. Following this, subjects made ratings
of the valence, arousal, and vividness of the emotional imagery.
Startle probes were presented either 12, 18 or 24 seconds into the 30
second imagery period. Factor analyses of subject's ratings of the
scripts allowed them to be placed into four groupings; (1) high
arousal, positive valence, (2) high arousal, negative valence, (3) low
arousal, positive valence, and (4) low arousal, negative valence. A
series of 2 x 2 ANOVAs indicated that although vividness ratings were
similar across the classes of scripts, startle magnitude was
significantly greater during the two high arousal scripts than the two
low arousal scripts. Emotional valence did not have a significant
influence on startle magnitude. These results suggest that the
emotional determinants of startle reflex magnitude differ between
perception of internally generated and externally generated emotional
stimuli.
Effects of misinformation on the Concealed Knowledge Test
Susan Amato-Henderson1, Charles R. Honts2, and Joseph J. Plaud1
1University of North Dakota, 2Boise State University
The current study used a repeated measures design to examine the
effects of misinformation on the validity of the Concealed Knowledge
Test (CKT). Ninety-six subjects were made knowledgable by watching a
12-minute videotaped crime of a burglary. One week later subjects were
given misinformation concerning three details of the crime. The
misinformation was contained in a narrative presented to the subjects
as a memory refresher. Subjects then took the CKT, which inquired
about 3 non-misinformed and 3 misinformed crime details. The
non-misinformed CKT series consisted of the key and 5 foils, whereas
the misinformed series consisted of the key, the misinformation and 4
foils. To determine the effect of misinformation on CKT performance,
skin resistance amplitude data was scored using Lykken's procedure
(1959, Journal of Applied Psychology, 43, 385-388). Scores on the 3
non-misled series (M = 3.57, SD = 1.65) were significantly larger than
scores on the three misled series [M = 2.52, SD = 1.71; t(91) = -4.80,
p < .000]. Furthermore, no significant differences existed between
scores associated with the key (M = 2.52, SD = 1.71) on the
non-misinformed series and scores associated with the misinformation (M
= 2.46, SD = 1.54) on the three misled series [t(93) = .24, p =.813].
In real-world applications it would not be possible to differentiate
misinformed items from other foils. Results of this study suggest that
the mere introduction of misinformation (rather than a demonstrated
misinformation effect) would lead to a higher rate of false negative
errors. These findings should lead one to question the utility of the
CKT in real-world situations due to the many possible sources of
misinformation to which a guilty individual may be exposed (e.g.,
inaccurate media reports, interrogation).
Effects of caffeine and expectancy of caffeine on the human startle
reflex
Siobhan E. Andrews1, Terry D. Blumenthal1, and Magne A. Flaten2
1Wake Forest University, 2University of Tromso
Repeated use of a drug such as caffeine may constitute a classical
conditioning procedure, where the effect of caffeine is the
unconditioned stimulus, and stimuli reliably accompanying the intake of
caffeine, e.g. the sight and smell taste of coffee, may constitute
conditioned stimuli that can elicit conditioned responses. An
experiment was performed that investigated the effect of caffeine and
expectancy of caffeine on the startle reflex (periorbital eyeblink
EMG). Nineteen habitual caffeine users received caffeinated coffee,
caffeinated juice, decaffeinated coffee, and decaffeinated juice in
four counterbalanced sessions spaced one week apart. Juice without
caffeine constituted the baseline, whereas juice with caffeine should
give information about the effect of caffeine without any conditioning
or expectancy effects. Responses to decaffeinated coffee should give
information about conditioned responses, and responses to the
caffeinated coffee should give information about the interaction of
caffeine with conditioned responses. The results showed that caffeine
increased startle eyeblink amplitude, but had no effect on startle
probability or latency. A caffeine by solution interaction was
significant for response latency. In the decaffeinated coffee
condition, subjects had significantly longer reflex latencies than in
the other three conditions, indicating that the ingestion of coffee may
have elicited a compensatory response that was overridden by the
caffeine response. Thus, two processes may have been acting at the same
time, a conditioned slowing of responding based on the expectation of
caffeine, and a speeding up of responding back to some optimal level by
caffeine itself.
Following the time course of feature extraction with event-related
brain potentials
Lourdes Anllo-Vento and Steven A. Hillyard
University of California, San Diego
During selective attention to multifeature stimuli, it has been
proposed that an initial stage of parallel feature extraction gives way
to attentive processing of feature conjunctions. This experiment was
designed to determine the time course and topographical distribution of
event-related potentials (ERPs) associated with selective processing of
color and orientation features and their conjunctions. ERPs were
recorded while subjects viewed foveally presented vertical or
horizontal red or orange bars and tried to detect infrequent
shortenings of one of the bars of the designated color and
orientation. EEG was recorded from 42 scalp electrodes and averaged
separately for each of the four color-orientation combinations under
each of four attention conditions, where each combination was attended
in turn. The ERP waveforms revealed several distinct phases in the
processing of color and orientation conjunctions. Between 100-200 ms
there was evidence of independent selection of color and orientation
features, but not of the relevant conjunction. At about 200 ms
post-stimulus, there was a significant attentional modulation due to
the selective processing of the relevant feature conjunction, along
with evidence of continued parallel processing of each of the two
features. A still later phase of the ERP waveform reflected selective
processing of the target feature of bar length. Thus, ERPs provide an
effective means of delineating the temporal course of independent and
conjunctive stages of feature selection.
Effects of personality on skin conductance habituation.
Peter Annas, Lisa Ekselius, Lars von Knorring, and Mats Fredrikson
Uppsala University,
Habituation is a form of non-associative learning by which the
organism learns not to respond to repeated irrelevant stimuli. Studies
have shown that anxious and neurotic subjects tend to habituate slower
than normal controls. However, results have been conflicting for
studies on sensation seeking and habituation. Both differences and
similarities between subjects being high in sensation seeking and
normal controls have been reported. The aim was to study habituation of
skin conductances responses in 190 subjects high or low (median split)
in somatic anxiety, psychastenia and monotony avoidance measured
through the Karolinska Scale of Personality. Both somatic anxiety and
psychastenia are components in neuroticism and monotony avoidance is
akin to sensation seeking. Skin conductance responses were measured to
4 seconds, 80 dB tones presented through headphones with an interval
ranging from 10 to 15 seconds. Subjects with high somatic anxiety and
psychastenia habituated significantly slower as compared to those being
low. A reversed pattern appeared for monotony avoidance. Subjects high
in monotony avoidance showed markedly faster habituation than those
being low. These results indicate that the anxiety component in
neuroticism is involved in determining habituation and that sensation
seekers, estimated through monotony avoidandce, habituate faster than
normal controls.
Genetic influences on the skin conductance orienting reaction to
fear-relevant and -irrelevant stimuli.
Peter Annas and Mats Fredrikson
Uppsala University
The orienting reaction reflects attention to novel stimuli. Previous
studies indicate enhanced orienting reactions to fear-relevant stimuli
(e.g. pictures of snakes and spiders) as compared to fear-irrelevant
stimuli (e.g. pictures of circles and triangles). The aim was to
investigate whether orienting reactions to these stimuli are
genetically determined. 77 monozygotic (MZ) and 72 dizygotic (DZ) twin
pairs were shown 4 slides with fear-relevant or fear-irrelevant
content presented for 8 seconds during which skin conductance were
measured. Skin conductance responses (SCR's) were range corrected and
averaged over trials. Correlations between SCR magnitude in twin pairs
were higher for fear-relevant than for -irrelevant stimuli for both
zygosity groups. The correlations in MZ twins was double that of DZ
twins for both types of stimuli indicating additative genetic effects.
With linear structual modeling a stronger genetic effect was evident
for fear-relevant stimuli than for fear-irrelevant stimuli. We
conclude that the orienting reaction in part is genetically modulated
and that the genetic influence is greater for fear-relevant than for
fear- irrelevant stimuli.
EEG correlates of psychometric intelligence in adolescents: Coherence
and dimensional complexity
Andrey P. Anokhin
Washington University School of Medicine
This study investigated relationships between global properties of
brain electric activity under different conditions and intelligence.
EEG was recordered monopolarly from 10 symmetric leads (10-20 system)
in 37 (17 males) healthy subjects (mean age 13.7 yrs) under resting
condition with eyes closed and during performance of two visually
presented cognitive tasks, verbal (semantic grouping) and spatial
(mental rotation). On another occasion, the subjects were administered
the Amthauer's Intelligence Structure Test (IST). Both total IST score
and some individual subtests of specific abilities showed significant
positive correlations with EEG coherence in the theta band and
significant negative relationships with the correlation dimension of
the EEG (a measure reflecting the complexity and unpredictability of of
neural dynamics underlying the EEG time series). Furthermore these two
EEG parameters were inversely related to each other. Taken together,
these EEG metrics accounted for about 30% of the total IQ variance in
this sample. No significant effects of the task type (spatial vs.
verbal) or specific abilities were observed. Long-distance coherence
indices (fronto-parietal and fronto-occipital) showed the most
consistent relationship with cognitive abilities. The results suggest
that the order to chaos ratio in task-related brain dynamics may be one
of the biological factors underlying cognitive performance in
adolescents.
The role of stimulus preceding negativity and heart rate deceleration
as an index of attention
Ross Apparies, Brad Hatfield, Laine SantaMaria, and Thomas Spalding
University of Maryland
The current study endeavors to directly assess the role of attention
in eliciting the SPN, and to identify the SPN's relationship with heart
rate deceleration (HRD). Accordingly, 20 right handed college age
males performed a cued discrimination and reaction time task. This
task consisted of a tone (S1) which provided information about the
upcoming difficulty of S2, (consisting of two bars of varying height,
easy difference 3", difficult difference 1/4") presented on a computer
screen for 100 ms. Since the subject was only required to make a
decision of which bar (right or left) was higher, the S1-S2 interval
was not contaminated by motor preparation. The subject was required to
respond according to their decision at S3. EEG, referenced to average
ears, was obtained at C3, C4, P3, and P4, using a lowpass filter of 30
HZ, and amplified 50,000 times. Heart rate was obtained in interbeat
intervals accurate to the millisecond.
The EEG data were subjected to a 2 x 2 x 2 (Difficulty x
Laterality x Region) ANOVA. This ANOVA yielded no significant
effects, however the trends in the data show that the difficult
discrimination is preceded by a greater negativity then the easy
discrimination. The HRD data, which was subjected to a t-test, found
significant differences between the easy and difficult trials.
Although the trends in the SPN and HRD data are in the same direction,
no correlation was found between these measures. The trends suggest,
that the SPN and HRD, show increased effects prior to a task that
requires increased cognitive demands.
Event-related potentials during recognition memory for pictures
Maria Luisa Armilio, Terence W. Picton and Fergus I.M. Craik
University of Toronto
Event-related potentials (ERPs) were recorded from 46 electrodes
during encoding and retrieval of complex, coloured pictures. Subjects
determined whether the pictures were 'old' (seen previously) or 'new'
(never before presented) during recognition. All responses during
recognition showed an N150 and a prominent P240 over occipitoparietal
sites; both waves were larger over the right hemisphere. These may
represent the automatic processing of nonverbal stimuli. A frontal
negativity at 450 ms (N450) that was more prominent to correctly
recognized new pictures may signify some early memory process
associated with novelty detection. The successful retrieval of the old
pictures from memory may be denoted by the centroparietal positive wave
(P550) that was more prominent and earlier in latency to correctly
identified old pictures. Beginning at approximately 600 ms, a positive
slow wave arose over prefrontal sites in some subjects and lasted until
the end of the recording epoch. This was more positive in the ERPs
elicited by the new pictures and suggests some further processing of
those stimuli recognized as novel. These late, cognitive components
provide a likely time course for these operations in memory.
Slow cortical positivity in 6-year-old children during an S1-S2
paradigm
Gregory J. Austin, W. Keith Berg, and Helen Fields
University of Florida
During a fixed-foreperiod interval, adult's slow brain potential moves
negatively in a pattern known as the CNV. To our knowledge there is no
published study of this phenomenon in young children. However, Warren
and Karrer's (1992, Annals of the New York Academy of Sciences, 425,
489-495) report of brief positive premotor potentials suggests
children's slow potentials may differ from adults.
Both adults (N=20) and 6-year-old children (N=16) were presented
with 30 and 28 trials respectively in which a warning light was
followed after 6 seconds by an interesting, age-appropriate video was
presented as a "go" stimulus for a speeded button press. Slow brain
potential from Cz and vertical EOG were recorded with a 18 s time
constant as was second-by-second HR.
Adults showed the typical slow negativity gradually increasing
over the 6 s interstimulus interval as well as the typical three
component anticipatory HR pattern. In contrast, the children's slow
cortical potential was significantly positive during the interval as
demonstrated by a linear seconds effect, F(1,15) = 9.25, p < .01. The
heart rate pattern was very similar to adults. EOG was not
consistently correlated with brain potential, being positively
correlated on some slow positive trial blocks, and negatively
correlated on others. Of the 16 subjects, 11 showed clearly positive
slow potentials, 3 little or no slow change, and 2 negative change.
Careful examination of the ERP to the warning onset verified that lead
polarity was not inadvertently reversed.
The results suggest that cortical dipoles associated with slow
potentials must undergo dramatic changes between the ages of 6 and
adulthood, possibly indicative of major brain reorganization.
Vocal expression of emotion is associated with vocal fold vibration and
vocal tract resonance
Jo-Anne Bachorowski1 and Michael J. Owren2
1Vanderbilt University, 2Reed College
Acoustic properties of speech likely provide external cues about
internal emotions, a phenomenon called "vocal expression of emotion."
Most empirical work in this area has emphasized global measures, such
as pitch and speech rate. In this experiment, associations between
induced positive and negative emotions and more fine-grained acoustic
characteristics were examined. Twelve subjects were shown 20 slides
selected from the International Affective Picture System to elicit
emotional responses ranging from strongly negative to strongly
positive. Following each slide presentation, subjects provided a
free-form description of the feelings and thoughts evoked by the
picture, preceded by the stock phrase "This test picture..." At the
end of this narrative, subjects prompted for the next slide by saying
"Next test picture." Acoustic analyses of the frequency and spectral
properties of the /e/ phoneme, drawn from the word "test" in each stock
phrase, showed statistically significant interaction effects involving
emotional valence and trait differences in emotional intensity.
Discriminant function analyses indicated that acoustic cues associated
both with vocal tract resonance and vocal fold vibration rate and
variability are related to discrete emotional states. The effects
observed are of sufficient magnitude to be perceptible, and indicate
that an emotion experienced during vowel production can affect the same
acoustic cues widely held to be used in a listener's speech processing.
These results demonstrate both that acoustic properties of speech carry
information about emotional processes and that individual differences
in intensity of typical emotional responding may be an important
mediator of form of expression.
Psychophysiological responses to emotion-antecedent appraisal of
critical events in a computer game
Rainer Banse1, Alexandre Etter2, Carien van Reekum2, and Klaus R.
Scherer2
1Humboldt University, Germany, 2University of Geneva, Switzerland
A computer game was used to investigate psychophysiological reactions
to emotion-antecedent appraisal. Three appraisal dimensions were
studied in a factorial design: pertinence and conduciveness of an event
to the major goal in the game, and intrinsic pleasantness of game
events. Appraisals of goal conduciveness vs. goal obstruction were
operationalized by selecting critical game events in which the player
either succeeds to pass to a higher level or looses a 'life'. The
current level of the player's performance relative to his or her
personal high score was used to operationalize the pertinence of an
event to the current goal. Intrinsic pleasantness was manipulated by
presenting either pleasant or unpleasant sounds marking the critical
game event. 29 subjects practiced the game and then played for 45
minutes. Emotion self report was assessed for a sample of critical
events. Cardiac activity, respiration, skin conductance, skin
temperature, and EMG at the frontalis lateralis, left and right forearm
extensor muscle sites were continuously recorded. The self report data
indicate that appraisals induced the intended emotions: subjects
reported more joy/amusement and pride after goal conducive events, and
more anger after goal obstructive events. The factors conduciveness and
pertinence accounted for more and stronger psychophysiological effects
than intrinsic pleasantness. This result suggests that the pertinence
of an event to goals with high priority may moderate the link between
appraisal and physiological reactions. The specific results are
discussed in the framework of the component-process theory of emotion
(Scherer, 1986). This research was supported by the Swiss National
Fund for Research
Speed of processing and tested intelligence: A chronopsychophysiological
analysis
Theodore R. Bashore
University of Northern Colorado
Reaction time (RT) studies suggest that faster processing time is
associated with higher levels of tested intelligence. However, these
studies have not determined if differences in speed are evident at all
or only some stages of processing. To examine the extent to which
higher levels of intelligence are associated with general or
stage-specific benefits to speeded decision-making, 68 young adults
(mean age=28), grouped according to full scale WAIS IQ scores (105,113,
124, 134), completed a choice RT task in which stimulus
discriminability and S-R compatiblity were manipulated orthogonally.
Stimulus discriminability was varied by requiring subjects to respond
to the word LEFT or RIGHT, embedded in a matrix of number signs (#) or
of letters chosen randomly from the sets A-G or A-Z. S-R compatibility
was varied by requiring subjects to press a button with either the hand
indicated by the target word or the opposite hand. ERP activity was
recorded from Fz, Cz, Pz, and Oz. The choice reaction elicited a
series of components in the ERP, identified as the N60, N160, P200,
N260, and P300. Differences related to IQ were found only for N260
latency and RT. These differences indicated that the slowing incurred
when an incompatible response was executed reduced in magnitude as IQ
increased. This pattern of results suggests that the benefit in
processing speed that accrues to those with higher tested IQs is not
general, but derives from the speed with which they are able to select
a response output.
Frontal P300 decrements, childhood conduct disorder, and the prediction
of relapse among abstinent cocaine abusers
Lance O. Bauer
University of Connecticut School of Medicine
P300 event related brain potentials were studied in 49 cocaine
dependent patients, abstinent for 1-5 months, and 20 healthy,
non-drug-dependent controls. Patients were assigned to one of two
subgroups based on the presence/absence of a DSM-IIIR diagnosis of
antisocial personality disorder (ASPD). Analyses of P300s recorded
during a visual discrimination task (rare target, rare nontarget,
frequent nontarget) revealed reduced amplitudes at frontal electrode
sites among patients with ASPD, relative to the ASPD negative patient
and control groups. The frontal P300 decrement was only present in the
rare nontarget ERP. It correlated significantly with the number of
childhood conduct disorder symptoms, but not with the number of adult
ASPD symptoms. A secondary analysis examined the relationship between
P300 amplitude among cocaine dependent patients and their future
behavior, i.e., relapse versus continued abstinence.
Discriminant function analysis revealed that P300 amplitude alone
accurately identified 70.6 % of the patients who would later relapse,
and 46.7 % of the patients who did not.
Paternal alcoholism and smooth pursuit eye movement abnormalities in
abstinent cocaine abusers
Lance O. Bauer.
University of Connecticut School of Medicine
The present study evaluated smooth pursuit eye movement (SPEM)
function in 36 cocaine-dependent patients, abstinent for 3 months, and
12 non-drug-dependent normal volunteers. None of the subjects in
either group
met DSM-IIIR diagnostic criteria for schizophrenia, or delusional,
major affective, or schizotypal personality disorders. None possessed
a history of seizures, significant head injury, or HIV-1 infection.
Forty-eight percent of the cocaine-dependent patients also met criteria
for alcohol dependence.
Subjects were medication-free at the time of testing. SPEMs were
elicited by a pendulum, oscillated at 0.5 Hz, and recorded using
electro-oculographic techniques. Tracking accuracy was estimated by
the power of the horizontal EOG at the stimulus oscillation frequency.
Analyses revealed above normal SPEM tracking performance among patients
with no paternal history of alcoholism, which correlated positively
with years of cocaine use; and subnormal SPEM tracking among patients
with a paternal history of alcoholism. These differences could not be
explained by other family history, demographic, or drug use variables.
The effect of hypoxia on the preprocessing stage in an auditory oddball
task employing reaction time and P300.
Catherine Beach and Barry Fowler
York University
An Additive Factors Method experiment was conducted to investigate
the slowing effects of hypoxia at the preprocessing stage, using
auditory reaction time (RT) and P300 latency. Hypoxia was induced with
low oxygen mixtures and controlled by maintaining saturated
oxyhemoglobin at 65%. Two equiprobable intensities were presented in
an oddball task to 12 subjects, who pressed one of two finger switches
when they heard the tones. RT and P300 latency increased in response
to both low-intensity tones and hypoxia, resulting in an interactive
effect on RT but an additive effect on P300 latency. P300 amplitude
was not affected by intensity or hypoxia. The results from this and
previous visual hypoxia experiments in our laboratory show a consistent
pattern of slowing at the preprocessing stage of information
processing, while central processing stages are unaffected. Two
explanations are presented to account for this pattern which
contradicts the accepted global impairment view that hypoxia causes a
generalized impairment of cognitive functions.
Frontal EEG activation in 8-month-old infants during a looking version
of the classic A-not-B object permanence task
Martha Ann Bell
Virginia Polytechnic Institute and State University
A looking version of the classic Piagetian object permanence task
(A-not-B) was designed to allow recording of EEG activity during this
marker of sensorimotor development. The reaching movements required by
the infant in the classic version negate use of EEG during the task. A
large body of EEG work with adults forms the core of our scientific
knowledge of mature brain function during cognition. Knowledge of adult
cognitive processing is not applicable to infancy, however.
Sixty-three 8 month-old infants were assessed on both the reaching
and the looking versions of the A-not-B task, with EEG recorded during
looking. Order of testing was counterbalanced, with a one-minute
baseline EEG recording made just prior to the looking task. EEG was
recorded from 6 anterior and 4 posterior scalp locations.
Infants in this within-subjects design performed at a higher level
on the looking version of the A-not-B task than on the reaching
version. This is consistent with recent between-subjects research
using a Delayed Response reaching versus looking paradigm (Hofstadter &
Reznick, 1996, Child Development, 646-658) and may reflect the simpler
response required by looking compared with reaching. There were
activation differences between baseline and task-related EEG recordings
for the frontal (F3/F4) scalp leads, but not for the posterior leads.
Performance on the classic reaching version of A-not-B has been
associated with maturation of the frontal cortical area, measured via
baseline EEG (Bell & Fox, 1992, Child Development, 1142-1163). These
data suggest that it is possible to study infant brain function during
classic cognitive tasks associated with the sensorimotor period of
development.
Effects of substituting components of nonsignificant stimuli on
reinstatement of the electrodermal orienting responses and
dishabituation
Gershon Ben-Shakhar, Itamar Gati, and Naomi Benbassat
The Hebrew University, Jerusalem
This study examined several aspects of a feature-matching theory (Gati
& Ben-Shakhar, 1990, Journal of Experimental Psychology: General,
251-263) formulated to account for the roles of stimulus novelty and
significance in psychophysiological orientation processes. The
prediction that stimulus novelty is negatively related to the measure
of common features, shared by the stimulus input and representation of
preceding events, and positively related to the measure of their
distinctive features was tested. A simple habituation paradigm was used
and sequences of nonsignificant verbal (descriptions of people) and
pictorial (schematic faces) compound stimuli were presented to 80
subjects. A test stimulus (TS) was presented after 9 repetitions of a
standard stimulus (SS), followed by 3 additional repetitions of SS. TS
was created by substituting 0, 1, or 2 stimulus components of SS, and
stimulus change was manipulated both within categories (e.g.,
substituting one type of glasses by another type) and between
categories (e.g., substituting glasses by a hat). The dependent measure
was the electrodermal component of the OR to both the TS (OR
reinstatement) and the SS immediately following TS (dishabituation). As
predicted, OR reinstatement was affected by substituting components,
and between-categories substitution was more effective than
within-categories substitution. However, OR magnitude was unaffected by
the number of substituted components, and no dishabituation effects
were obtained. The same pattern of results was obtained regardless of
whether verbal or pictorial stimuli were used.
Affect and unconscious processing: An event-related potential study
Edward Bernat1, Scott Bunce1, Howard Shevrin1, Stephen Hibbard2, and
Mike Snodgrass1
1University of Michigan, 2Pacific Graduate School of Psychology
This study investigates the relationship between the experience of
positive and negative affect and parameters of the ERP associated with
conscious and unconscious processes. Specifically, we hypothesized
that: 1) Negative ratings (unpleasant stimuli) would be correlated with
ERP amplitude positivity. 2) Subject ratings of the stimuli would show
some systematic relationship with the subliminal ERPs (Shevrin, et al,
Consciousness and Cognition, 1992, 1, 340-366). Two sets of data were
analyzed: one set used words as stimuli and the other used schematic
faces (happy/sad). All stimuli were presented at subliminal and
supraliminal durations. The data were analyzed using standard
components within a one second ERP window (N1, P2, P3, N4). The data
using words were analyzed for affect valence using individual subject
ratings on the Osgood evaluative dimension which is made up of five
items. Both the means and standard deviations among the items were
analyzed. Osgood means predicted component amplitudes across durations
and electrodes; a lower mean (more negative rating) was associated with
a more positive component amplitude (F=6.3, p 800 ms),
blink responses were potentiated for unpleasant pictures, compared to
pleasant stimuli. Responses in skin conductance and corrugator EMG
systems were also identical to those obtained with a 6 s viewing
interval. These data suggest that, in the absence of a perceptual
mask, picture processing follows the same time course regardless of
whether the visual stimulus is present or absent, and that startle
reflex modulation indexes the affective quality of a persisting mental
representation.
Effects of posture on autonomic reactivity to psychological stress in
women
Beth Colaluca1, Kathleen Soderlund1, and Robert M. Kelsey2
1University of North Texas, 2State University of New York at Stony Brook
The effects of posture on cardiovascular and electrodermal reactivity
to psychological stress were evaluated in 28 undergraduate women during
two 5-min mental arithmetic tasks. Subjects performed one task while
sitting and the other task while standing, with each task preceded by a
5-min baseline period in the same posture. Half of the subjects
received the sitting baseline and task periods first, and the other
half received the standing baseline and task periods first.
Cardiovascular measures included heart period (HP), preejection period
(PEP), and total peripheral resistance (TPR). Skin conductance
responses (SCRs) served as a separate index of sympathetic activation.
During the baseline periods, standing was associated with shorter
HP, longer PEP, and more SCRs as compared to sitting (pright EDR asymmetry replicated previous
associations with the Active syndrome including thought disorder,
hallucinatory behaviour, and perseveration. The left>right asymmetry
was also associated with WCST perseverative errors. Distinguishing
between the frontal systems holds promise in elucidating
psychophysiological findings in schizophrenia and the
substrate of different syndromes.
Lateral asymmetry of slow potentials: Learned control and individual
differences.
John Gruzelier1, Elinor Hardman1, Kate Cheesman1, Ceri Jones1, David
Liddiard1, Hans
Schleichert2, and Niels Birbaumer2.
1Charing Cross and Westminster Medical School, 2Psychological
Institute,Tubingen
While learned control of slow potentials is well documented, we know
of no reports of the control of lateral asymmetries generated from
bipolar recordings. Two experiments are presented. Following work at
Tubingen feedback took the form of a small rocket, placed centrally on
a VDU screen and moved in accord with discriminant stimuli. Here rocket
ascent (A-trial) indicated a leftward hemispheric shift and descent (B-
trial) a rightward shift. Subjects participated in three sessions of 60
psuedo-randomly ordered eight second trials in three blocks with a four
second intertrial interval. In experiment I using bipolar recording
from C3-C4 subjects (N=15) were assisted with a strategy to concentrate
on the contralateral arm. Subjects were surprisingly successful in
learning control as shown in a MANOVA (Session, Block, Stimulus A/B),
in which there was a main effect of Stimulus (F(1,14)=14.38, p<0.002)
without effects of Session or Block, or interactions. On A trials there
was a leftward shift (-0.69) and on B trials a rightward shift
(+1.52). In experiment II recording was from F3 and F4 and subjects
(N=16) were divided into a strategy (positive versus negative emotion)
and no-strategy group. Asymmetry control was achieved in the third
block of trials in all sessions, where there was a main effect of
Stimulus (p<0.001). Individual differences in attention and schizotypy
were associated with control of asymmetry:- Extremely Focused Attention
(Crawford), Absorption (Tellegen and Atkinson), Unreality (Gruzelier),
as was a rightward shift. Neurophysiological and clinical implications
will be discussed. (Supported by a NARSAD Senior Investigator Award).
Prepulse modulation before and after pallidotomy in patients with
Parkinson's Disease
Paul Haerich1, Amy D. Clegg1, and Robert P. Iacono2
1Loma Linda University, 2School of Medicine, Loma Linda University
Parkinson's Disease is a neurodegenerative disorder in which the
nigral dopamine input to the striatum progressively declines resulting
in, inter alia, increased activity among GABAergic cells in the
posteroventral pallidum. These pallidal neurons produce two major
projections: the first to the thalamus which is associated with tremor
and dyskinesias, the other to the pedunculopontine tegmental nucleus
which is thought to play a role in the stiffness and bradykinesia
characteristic of Parkinson's Disease. Pallidotomy is a neurosurgical
technique in which these cells are lesioned in order to provide
reduction in the severity of parkinsonian symptoms including tremor,
rigidity, and akinesia. Individuals undergoing therapeutic pallidotomy
were tested before (1 or 2 days) and after (5 - 8 days) surgery.
Reflex blinks were elicited with airpuffs (20 kPa, 100 ms duration)
directed 1 cm laterally to the outer canthus of the left eye. A
vibrotactile stimulus affixed to the middle finger of the right hand
was used as a prepulse. Each test session consisted of 60 airpuffs (12
blocks of 5 trials). One trial in each block presented the airpuff
alone; in the others the vibrotactile stimulus was presented 200, 350,
1000, or 2000 ms prior to and terminated with the onset of airpuff.
Results suggest that following pallidotomy at both short and long lead
intervals (a) prepulse modulation of blink amplitude is significantly
reduced (p = .05), while (b) the probability of a reflex blink is
increased (p < .02). These results confirm in humans observations in
which lesions of the striato-pallidal-pedunculopontine circuitry
decrease prepulse modulation in laboratory rats.
Anterior EEG asymmetry and facial EMG as evidence that affect is
involved in the mere exposure effect
Eddie Harmon-Jones1 and John J. B. Allen2
1University of Texas -- Arlington, and 2University of Arizona
Explanations of the mere exposure effect assume that familiar stimuli
evoke more positive and/or less negative affect than unfamiliar
stimuli. In an experiment designed to test this assumption,
participants repeatedly viewed photographs of women's faces and then
viewed these women again (familiar) and novel women (unfamiliar) while
EMG activity in the zygomatic and corrugator muscle regions was
recorded. Familiar stimuli were rated more positively than unfamiliar
stimuli (mere exposure effect), and they evoked more EMG activity in
the zygomatic region. We also hypothesized that individual differences
in motivation and affect would interact with reactions to merely
exposed stimuli. To test these hypotheses, at baseline we assessed
participants' self-reported affect, and recorded 4 min of resting EEG
at F3, F4, P3, and P4. Asymmetrical EEG activity scores were computed
by subtracting log alpha power at F3 from log alpha power at F4, so
that higher scores reflect greater left than right activity. Anterior
EEG activity was recorded because much research has found that the
anterior regions of the left and right hemispheres are specialized for
expression and experience of approach and withdrawal motivation,
respectively. Individuals with relatively less left anterior
activation evidenced a greater mere exposure effect. Individuals
reporting less positive affect and individuals reporting more negative
affect at baseline evidenced more zygomatic muscle region activity to
the familiar than to the unfamiliar. These results implicate affect in
the mere exposure effect, and suggest mere exposure increases positive
affect rather than decreases negative affect.
Anger and prefrontal brain activity: EEG asymmetry consistent with
approach motivation despite negative affective valence
Eddie Harmon-Jones1, John J. B. Allen2, and Ernest S. Barratt3
1University of Texas -- Arlington, 2University of Arizona, 3University
of Texas Medical Branch at
Galveston
The anterior regions of the left and right hemispheres have been
posited to be specialized for expression and experience of approach and
withdrawal processes, respectively. Much of the evidence supporting
this hypothesis has been obtained using EEG activity, particularly
power in the alpha band (8-13 Hz), which has been found to relate
inversely to activity. Moreover, anterior asymmetrical activity has
been posited to function as a diathesis that predisposes persons to
respond with approach or withdrawal processes given appropriate
situations. Much research has supported these hypotheses. However, in
most of this research, motivational direction has been confounded with
affective valence, such that, for example, approach motivation has been
associated with positive affect. In the present research, we tested
the idea that dispositional anger, an approach-related motivational
tendency with negative valence, would be associated with increased left
anterior activity. Adolescents' EEG during 3 min of eyes-open and 3
min of eyes- closed resting periods was recorded. Frontal and parietal
asymmetrical activity (log F4 - log F3, log P4 - log P3, so that higher
scores reflect greater left than right activity) were examined in
relation to scores on the Buss and Perry (1992, Journal of Personality
and Social Psychology, 452- 459) aggression questionnaire. The
anterior asymmetry correlated positively and significantly with trait
anger, suggesting that increased relative left frontal activity was
associated with increased trait anger. No significant relationships
with parietal asymmetry occurred. These results suggest that the
anterior asymmetry varies as a function of motivational direction
rather than affective valence.
Implicit memory bias for threat: A state manipulation
Lesley K. Harrison and Graham Turpin
University of Sheffield
Previous research has revealed equivocal findings concerning a threat
bias in implicit memory. This study sought to demonstrate such an
effect by exposing high and low trait anxious students to a state
anxiety manipulation using examinations. Hypotheses proposed that
elevated state anxiety would increase recall for threatening
information. In addition, psychophysiological responding to threat and
non-threat words during the priming phase would relate to performance
on a subsequent implicit memory task. Subjects (N=40) were allocated
to two equal groups; each tested during an exam and non-exam period.
All subjects viewed words (20 threat, 20 non-threat), presented for a
duration of 3s, with an ITI of 25s to 35s. A filler task and word-stem
completion task followed the priming phase. Heart rate, skin
conductance and respiration were measured throughout the experiment
using a Biopac system. High and low trait anxious subjects were equally
allocated to each group. State anxiety was significantly elevated
during the exam test session (p.05), on
any of the dependent measures. EMG activity of orbicular oculi
correlated negatively with ratings of affect, Spearman rho (5) = -.89 ,
P < .05 (film-set 1) & rho (5) = -0.94, P < .01 (film-set 2). Film
clips were evaluated with respect to their reliability (test-retest and
parallel form) in modulating acoustic startle reflexes to white
noise-bursts.
Startle reflex modulation effects using these film stimuli were
sufficiently powerful and consistent to indicate that the
procedure is promising as a measure of emotional states with
application to personality differences, psychotropic drug effects and
treatment outcome studies.
Dissociation of ERP topographies for verbal and nonverbal auditory
oddball tasks using principal components analysis
Jurgen Kayser, Craig Tenke, Jennifer Watson, and Gerard Bruder
New York State Psychiatric Institute
ERP asymmetries were examined in twelve normal right-handed subjects
during oddball tasks using binaurally presented verbal (consonant-vowel
syllables) and nonverbal (complex tones) stimuli (20% targets).
Response hand was counterbalanced across subjects. ERPs were recorded
from 30 scalp electrodes. A principal components analysis with varimax
rotation performed on ERP waveforms revealed five factors (92.2%
variance) identified as N1 (peak latency 100 ms), P2/N2 (200 ms), early
P3 (300 ms), late P3 (430 ms), and slow wave (500-1000 ms). Factor
P2/N2 loaded on P2 for nontargets and on N2 for targets. Repeated
measures ANOVAs of factor scores showed enhanced N2, early P3, and late
P3 for targets compared to nontargets, but not N1 or slow wave. For
targets, significant task (verbal/nonverbal) x hemisphere interactions
were found for N2, early P3, and late P3. In the nonverbal task, N2 was
maximal over the right hemisphere, particularly over lateral-temporal
regions. For the verbal task, N2 was maximal over the left hemisphere,
particularly over lateral-parietal regions. Early P3 was present only
in the nonverbal task, while late P3 was present in both oddball tasks.
Early and late P3 components both inverted frontally and were largest
at Pz. Early P3 was more pronounced over the right hemisphere (greatest
asymmetry at medial-central sites), while late P3 was more pronounced
over the left hemisphere, particularly for the verbal task (greatest
asymmetry at parietal-temporal sites). These distinct, asymmetric ERP
topographies presumably reflect differential involvement of cortical
structures in identification of phonemes (left parieto-temporal) and
complex tones (right anterior-temporal).
Effects of text connectivity on colour-cued selective attention
event-related potentials (ERPs)
Marion Kellenbach and Patricia Michie
1Groningen University, 2University of Western Australia
Recent evidence has suggested ERPs associated with colour-cued
selective attention may be modulated by language variables. In
contrast to the selection negativity previously reported in colour-cued
selection studies, a long duration midlatency positivity associated
with attention (selection positivity) was recently reported in a
colour-cued selective attention paradigm utilising connected text
stimuli (Nobre and McCarthy, 1987, Society for Neuroscience Abstracts,
13, pp. 852). Three experiments investigated this polarity reversal of
colour selective attention effects on ERPs by systematically varying
features of the Nobre paradigm, including the connectivity of the text,
type of target stimuli, type of response, inclusion of function words
and word repetitions, and stimulus onset asynchrony (SOA). The
selection positivity was reliably elicited, and shown to be comprised
of several overlapping subcomponents distinguishable on the basis of
latency, scalp distribution, and the independent influences of text
connectivity and SOA variables. In addition, an unprecedented colour-
selection enhancement of the exogenous P1 component, previously thought
to form part of the ERP signature unique to spatial selection, was also
observed. Elicitation of this early effect was shown to be sensitive
to task demands as defined by response type. The implications of these
findings for the temporal and neuroanatomical organisation of cognitive
processes are considered, and the data are interpreted within the
context of a parallel, interactive attentional network under the
control of an executive attentional system.
Reactivity and resiliency in older adults
Arlene R. King, Marcia Taborga, and Robert W. Levenson
University of California, Berkeley
Significant relations between life stress and disease have been
reported frequently. However, effect sizes are typically small and
individual differences abound. We used these individual differences to
operationalize the construct of "resiliency" as the likelihood of
remaining in good health given high levels of life stress. We
hypothesized that people who show such resiliency will also be less
physiologically reactive to more acute stressors.
To increase variability in health outcomes, we studied an older
sample than is typical for this research. Stressful life events (over
the past year) and illness symptoms were assessed by questionnaire.
Resiliency was operationalized as the residual scores when illness data
were regressed on life stress data, thus indicating whether the person
had more illness (low resiliency) or less illness (high resiliency)
than would be expected based on the amount of life stress experienced.
Physiological (cardiovascular, electrodermal, somatic)
responses of 58 older married couples (average age:
husbands=64, wives=62) were studied in the laboratory during a
15-minute discussion of a mutually-distressing relationship issue.
Reactivity scores were calculated by subtracting the average
physiological levels during a five-minute silent pre-interaction period
from the average levels during the 15-minute discussion.
Results indicated that resilient individuals were less
cardiovascularly reactive to the stressful interaction (smaller heart
rate increases, less shortening of pulse transmission times to the ear
and finger). We conclude that lower physiological reactivity to acute
interpersonal stress may help explain why some older people are more
resilient to life stress-related diseases.
Dimensional complexity of the EEG in schizophrenics under cognitive
challenge: Differences to normal subjects.
Peter Kirsch, Christoph Besthorn, Jochen Rindfleisch, and Robert Olbrich
Central Institute of Mental Health
The calculation of the fractal dimension is a rather new and rapidly
growing approach of analyzing the human EEG basing on chaos theory or
the theory of non-linear systems. It was demonstrated that the
complexity of the EEG signal differs in dependence of the psychological
state of the organism. While the complexity of the signals decreases
with the increasing depth of sleep, an increase of the dimension was
found under task compared to resting conditions. Analysis of the EEG
in schizophrenics showed an increased dimensional complexity under
resting conditions. These results were interpreted as reflecting the
looseness of thoughts often found in these patients. The aim of the
present study was to investigate whether or not schizophrenic patients
show different responses to cognitive challenge compared to normal
control subjects. It was expected that the complexity of the signal
under cognitive challenge is lower in schizophrenics than in normal
control subjects reflecting the impaired information processing
abilities of the patients. 87 schizophrenic and 30 matched control
subjects performed two different types of the continuous performance
task. The EEG was analyzed by calculation the Grassberger-Procaccia
correlation dimension. The results revealed no differences between
schizophrenics and controls under resting condition. In contrast,
during the first minute under task conditions the control subjects
showed a significant decrease of the dimension while no changes were
found for the schizophrenic group. These results occurred for both
types of the cognitive task. The results are interpreted as reflecting
the ability of normal subjects to adapt their information processing
system to the cognitive challenge. In contrast, schizophrenic subjects
do not show any adaptation to the task.
Impaired information processing and autonomic conditioning in
schizophrenia
Peter Kirsch
Central Institute of Mental Health
A reduced acquisition of autonomic conditioned responses as well as
electrodermal nonresponding are often reported deficits of
schizophrenic patients. In the framework of cognitive approaches, these
deficits were interpreted as reflecting a reduced amount of controlled
information processing capacity in schizophrenics. It could be shown
that schizophrenics did not differ from normal subjects in their
responses to aversive unconditioned stimuli (UCS). In contrast, they
did not show a sufficient discrimination between a paired conditioned
stimulus (CS+) and an unpaired conditioned stimulus (CS-). The aim of
the present study was to investigate the relation between impaired
controlled information processing and autonomic conditioning in
schizophrenics. 15 schizophrenic patients and 15 normal control
subjects were investigated in a non aversive classical conditioning
procedure. A letter reproduction task served as UCS while the CS was a
screen providing information about the task. Electrodermal responses
(EDR) , heart rates and reaction times (RT) were used as dependent
measures. It was expected that, with respect to the physiological as
well as the behavioral measures, schizophrenics showed a poorer ability
to differ between different stages of CS information content than
normals. The results confirmed the expected differences. No
differences of the EDR to the different CS were found for the
schizophrenic group. In contrast, the normal subjects showed clear
evidence for differential conditioning. The same differnces between the
groups occured for the RT measures. We interpret the results as
indicators of the reduced amount of controlled information processing
acquired by the schizophrenic patients during conditioning.
The effects of emotional disclosure and traumatic life event history on
blood pressure and heart rate in college-aged females.
David J. Klein and John T. Cacioppo
The Ohio State University
Emotional disclosure, the verbal expression of facts and emotions
related to a traumatic event,has been found to have beneficial effects
on health outcomes and affect. It has been hypothesized that the
effects of disclosure result from the confrontation an upsetting event,
which decreases negative physiological effects of trauma-related
inhibition and rumination. Ninety-one female participants were
selected from over 400 based on answers to a questionnaire about their
traumatic event history. Two groups of subjects were formed from those
who either reported having experienced or reported having never
experienced a traumatic event (e.g., assault). Subjects then wrote in
groups of 5 or less for 30 minutes about one of three randomly assigned
topics: (1) their most traumatic experience (real disclosure
condition), (2) a traumatic event (described by a short paragraph) that
they never experienced according (imaginary disclosure condition), or
(3) the physical layout of the campus (no-trauma control). A month
later subjects were run individually at which time their cardiovascular
activity was recorded at one-minute intervals while they: (a) sat
quietly (baseline) and (b) talked anonymously into a tape recorder for
6 minutes about the facts and feelings surrounding the most traumatic
experience of their life (disclosure period). Results indicated that
those with a history of trauma had higher blood pressure and heart rate
across the trauma disclosure conditions. In addition, blood pressure
and heart rate were elevated during the disclosure period relative to
baseline for all those with and without a history of trauma and across
trauma-disclosure conditions.
Gender differences in susceptibility to vection-induced motion sickness
and gastric myoelectric activity
Alexandrea H. Klose, Lisa M. Willoughby, and Senqi Hu
Humboldt State University
The purpose of the present study was to investigate gender differences
in susceptibility to vection-induced motion sickness. Twelve men and
14 women sat in an optokinetic drum for 8 minute baseline and 16 minute
drum rotation periods. During the drum rotation period, subjects'
symptoms of motion sickness (SMS) were measured. Subjects'
electrogastrograms (EGGs) and the ratios of spectral intensity at 4-9
cycles per minute (cpm) between drum rotation and baseline periods,
gastric tachyarrhythmia, were obtained. Repeated measures of analysis
of variance on scores of SMS showed significant differences between men
and women, F(1, 24) = 3.94, p < 0.05. Women reported significantly
more severe symptoms of motion sickness than men while viewing the
rotating drum. The mean scores of SMS were 5.45 for men and 6.55 for
women. One-way analysis of variance on ratios of spectral intensity at
EGG 4-9 cpm activity between drum rotation and baseline periods
revealed a significant difference between men and women, F(1, 24) =
4.68, p < 0.05. Women developed more severe abnormal gastric
tachyarrhythmia than men. The mean ratios of spectral intensity at EGG
4-9 cpm were 2.07 for men and 3.54 for women. These results indicated
that women are more susceptible to motion sickness than men.
Can the temporal locations of heartbeat sensations be measured using a
simultaneity paradigm?
Kelley A. Knapp and Jasper Brener
SUNY at Stony Brook
In the method of constant stimuli (MCS) subjects judge whether tones
presented at various time intervals after the R-wave are simultaneous
with their heartbeat sensations. The median interval (MDI) chosen
under these conditions is assumed to identify when the heartbeat
sensation occurs relative to the onset of ventricular contraction. It
may be inferred that heartbeat sensations detected <100ms after the
R-wave are transduced through receptors in or close to the heart, while
sensations detected later are sensed by more peripheral receptors.
Thus, the MDI may help to identify broadly which receptors transduce
heartbeat sensations. The validity of the MDI as a measure of the
relative temporal locations of sensations was tested using vibrations
and tones. On the first of three sessions, 35 subjects adjusted (ADJ)
the time interval between vibrations and tones until the two stimuli
were simultaneous. Subjects then completed two tasks in which they
judged the simultaneity of vibrations and tones presented at 6
different interstimulus intervals. In MCS1 but not in MCS2, one of
these vibration-tone intervals was equal to the median of the ADJ
task. If the MDI is a valid measure of when the vibration is sensed
relative to the tone then all MDIs should be equal. However MDIs were
found to be significantly different: ADJ (20 ms), MCS1(14 ms), and MCS2
(4ms), indicating a degree of uncertainty in measuring the relative
temporal locations of sensations using the simultaneity paradigm. This
research was supported by NIH Grant #HL42366 to JB.
Event-related potentials during dual task performance: Tracking and
auditory discrimination
Timothy F. Knebel
NASA Langley Research Center
This study examined the relationships between tracking difficulty,
tracking error, counting error, and ERP amplitude during auditory
discrimination. Twenty-four dextral volunteers performed a tracking
task across three levels of difficulty while simultaneously counting or
ignoring tones of two different pitches. EEG was recorded and averaged
at frontal, central, and parietal electrode sites. Peak amplitude
measures were obtained for components: N1, P2, N2, and P3.
The amplitude of P3 was significantly diminished in the
difficult tracking level compared to the easy and medium
tracking levels. P3 amplitude was larger for counted stimuli
especially at the central and parietal regions. N2 amplitude was
greater for counted stimuli at the frontal region. Tracking error,
measured as root-mean-square error (RMSE), increased significantly from
the easy tracking level to the most difficult. N2 and P3 amplitudes
were significantly and negatively correlated with RMSE. Counting error
rate was negatively correlated with P3 amplitude. Results are
interpreted consistent with theories of selective attention and
resource allocation.
Cardiovascular load perception: Results from studies using the method
of reproduction vs. the tracking method
Volker Kollenbaum1, Bernhard Dahme2, and Guenther Kirchner2
1University of Kiel, 2University of Hamburg
The interoception of heart rate, systolic blood pressure and
myocardial metabolism have been studied in two separate experiments.
In both experiments subjects were confronted with three levels of each
of these three cardiovascular parameters during bicycle ergometer
testing. The intensity levels were 25, 50, and 75 % of the individual
range of aerobic load. In the first experiment the subjects had to
reproduce these same values of the parameter in question by regulating
the physical load of the ergometer, in the second experiments subject
had to estimate the level of the parameter in question and its decay
after load had stopped by a tracking device. In the first experiment
complete data were gathered from 14 subjects (7 f, 7 m), in the second
one from 18 subjects (8 f, 10 m). Reproduction or tracking accuracy
were taken as interoceptive indices. Heart rate and blood pressure
were measured beat to beat by a Finapres device, the myocardial
metabolism was determined by the Robinson-Index. By both methods
subjects underestimated heart rate. In regard to blood pressure both
methods show divergent results. There is no substantial bias in the
perception of the Robinson-Index. We found a high internal consistency
in heart rate reproduction, but no monotone consistency at all in blood
pressure reproduction. The physiological processes underlying
interoception and reproduction of cardiovascular load have to be still
explored. The clinical implications of the bias in heart rate
perception during cardiac load will be outlined.
A method for two-dimensional self-regulation of slow cortical
potentials: Toward non-motoric communication
B. Kotchoubey, H. Schleichert, W. Lutzenberger, and N. Birbaumer
University of Tuebingen
Healthy subjects were presented with a sequence of two alternating
tones with 2-s ISIs. Subjects learned to produce rhythmic oscillations
of their slow cortical potentials (SCP) by generating directed SCP
changes in certain intervals between tones, while a moving object on a
screen provided them with continuous EEG feedback. Furthermore,they had
to produce two different EEG signals: a) positive or negative SCP shift
atvertex, and b) SCP asymmetry between the right and the left central
area. Thus, four conditions were to distinguish: (1) larger Cz
negativity in the second half-cycle than in the first half-cycle (the
on-screen object moving upwards), (2) larger Cz negativity in the first
than in the second half-cycle(the object moving downwards), (3) C3 over
C4 dominance in the second ascompared with the first half-cycle
(rightwards), and (4) C4 over C3 dominance in the second as compared
with the first half-cycle (leftwards). In the first session, 14
subjects differentiated significantly between the conditions (1) and
(2), but not between (3) and (4). Later, five subjects participated in
6 to 15 training sessions; four of them demonstrated highly-significant
differentiation between the right and the left conditions as well. The
differentiation was achieved within less than 300 ms after the
discriminative signal, i.e.much faster than in studies employing
traditional SCP biofeedback technique. The data suggest a hope of the
possibility to control a cursor on a two-dimensional screen by means of
SCP, which can be applied in severe motor disorders where no other
means of communication exist.
Cardiac reactivity to food intake by dieting status and gender
Jean Kristeller, Jeff McKee, and Thomas Johnson
Indiana State University
Previous work by this investigator identified a tachycardic response
(8-10 bpm) during food intake (peanut M&Ms), modified by psychological
variables (anxiety and dieting concern). A tachycardic response to
sucking has been demonstrated in infants, but this tachycardic response
during food intake has otherwise not been well documented. This study
extends the investigation to a variety of foods and further examines
the effect of dieting concern (Restrained Eating) and gender. Heart
rate was measured on a continuous basis (using the BIOPAC system) in 16
female and 9 male undergraduates. After a resting baseline, subjects
ate, on signal, four foods (pretzels, chips, grapes, peanut M&Ms),
varying by sweet and fat level. Average heart rate was calculated over
each one minute eating trial. Heart rate increased significantly
(pude and amplitude analysis of ERP signals.
Dimensional complexity and nonlinearity of sleep EEG recorded from
insomniacs and normal controls
Derek Loewy1 and Walter Pritchard2
1University of Ottawa, 2R.J. Reynolds Tobacco Co.
The techniques of nonlinear dynamics were used to compare the sleep
EEG of chronic insomniacs and normal controls. Six subjects diagnosed
with chronic primary insomnia and six normal controls slept for one
night in a sleep laboratory. EEG was recorded from C3 referenced to
the right mastoid. Data were recorded with 12 bits precision, sampling
rate 240 Hz, and 0.3-60 Hz on-line filters. Ten second epochs of EEG
were analyzed. These were obtained during wakefulness with eyes open
(fixating) and with eyes closed. EEG data were also recorded during
the following sleep stages: Stage 1 (first epoch after sleep onset),
Stage 2 with "spindles", early Stage 2 without spindles (after first
spindle or "K-Complex"), late Stage 2 (last 1/3 of the night), slow
wave sleep, REM sleep with rapid eye movements ("phasic REM"), and REM
sleep without rapid eye movements ("tonic REM"). EEG "dimensional
complexity" (DCx) was estimated using the Takens-Ellner Method and
singular value decomposition. The embedding lag was determined using
the method developed by Rosenstein et al. (1994). A measure of
nonlinearity was also obtained by computing the difference in DCx
estimates for these original data and DCx estimates for surrogate data
sets generated using the Gaussian-distributed amplitude-adjustment
procedure. No significant differences in DCx were found between
insomniacs and normals for any wake/sleep stage. DCx was lowest for
Stage 2 with spindles and highest for Stage 1. Nonlinearity was found
to be significant for Stage 2 with spindles, phasic REM, and awake with
eyes open.
Effects of clonidine on event-related potential indices of auditory and
visual information processing
Christopher T. Lovelace1, Connie C. Duncan2, and Walter H. Kaye3
1National Institute of Mental Health, 2Uniformed Services University of
the Health Sciences,
3University of Pittsburgh
Clonidine, an alpha-2 adrenoceptor agonist, inhibits activity in the
ascending noradrenergic projections originating in the locus coeruleus
and terminating in the cortex; this system has been implicated in
arousal and attention. In separate testing sessions, eight healthy
adult women were given 0.5, 1.0, or 2.0 micrograms/kg intravenous
clonidine or a saline placebo in randomized order. Event-related
potentials (ERPs) were recorded while subjects performed choice
reaction time tasks. Two highly discriminable stimuli (auditory or
visual, in separate trial blocks) were presented with relative
probabilities of .10 and .90. The high dose increased reaction time
and decreased accuracy of responses in the auditory task. There was a
similar, though nonsignificant, effect on accuracy in the visual task.
The high dose also markedly reduced auditory P300, whereas no
significant changes in performance or P300 were observed following the
low or medium dose. Clonidine did not affect the amplitude of visual
P300 or slow wave in either modality. The medium and high doses
increased the latency of visual N100. Mismatch negativity (MMN) was
quantified in the auditory .10 - .90 difference ERPs. The low dose
reduced the amplitude of MMN, but the medium and high doses did not.
Clonidine did not affect MMN latency. The differential effect of
clonidine on auditory and visual P300 reinforces the view of separate
auditory and visual attentional systems, with greater resilience in the
visual system.
The influence of hunger on the evaluative process
D.I. Lozano and S.L. Crites
University of Texas at El Paso
A study of the effect of hunger on the evaluative process was
conducted. Event-related brain potentials and behavioral data were
recorded to assess the effects of hunger on 1) the categorization of
stimuli, as indexed by ERPs; and 2) the behavioral responses to
stimuli. Participants abstained from food for at least 15 hours prior
to the time of the experiment. The experiment required participants to
categorize trait adjectives, foods, and animals as positive or
negative. Participants were exposed to two blocks of 300 words, one in
which the context words (trait adjectives) were positive and one in
which the context words were negative. Both positive and negative
target words (foods and animals) were embedded in the positive and
negative context blocks. Participants were given a meal following
completion of the categorization task and were required to complete the
same categorization task following the meal. The ERP data show that
the amplitude of the P300 is larger following a meal, consistent with
previous research (Geisler & Polich, 1992, Psychophysiology, 76-85).
In contrast to previous findings, the amplitude of the P300 is larger
when positive items are embedded in a negative context than when
negative items are embedded in a positive context.
Event-related potentials and serial position effects with 12-item lists
D.I. Lozano, S. Moreno, J.V. Devine, and S.L. Crites
University of Texas at El Paso
Event-related brain potentials and behavioral data were collected to
probe stimuli in a serial probe recognition task. Participants were
presented with lists of twelve pictures followed by either a matching
or a non-matching probe. Serial position effects were examined by
selecting the matching probes from list items 1-3, 5-7, or 10-12. The
probe matched an item on the list on 50% of the trials. The behavioral
data show that responses were more accurate when probes were presented
at the end of the list than when probes were presented at either the
middle or beginning of the list. In addition,responses to the probes
at the end of the list were faster than the responses to either probes
at the beginning or at the middle of the list. As has been found
previously, the ERP waveforms evoked by matching and non-matching
probes began to differ around 200 ms following probe presentation.
Furthermore, there were differences in the ERPs according to the
position of the probes. The amplitude of a positive component
occurring around 300 ms following probe presentation was largest for
probes located at the end of the list. In addition, the amplitude of a
negative component occurring around 360 ms following probe presentation
was larger for probes that were located at the end of the list than for
those located at either the beginning or the middle of the list.
Cortisol reactivity, self-esteem, and depression
Kristen A. Luscher, Angela Scarpa, Christine N. Christensen, and Kadee
J. Smalley
Eastern Washington University
Previous literature has found a relationship between low self-esteem
and depression. The mechanism underlying this relationship, however,
has not been fully understood. One possible mechanism is cortisol
reactivity which has also been associated with depression. This
preliminary study investigates cortisol reactivity as a factor which
mediates or moderates the relationship between self-esteem and
depression.
Fifty-three participants (20 male), ages 19-58 (mean 27), were
exposed to two laboratory stressors (a set of uncontrollable stressors
and an anagram task). Self-report self-esteem and mood ratings were
obtained prior to the stressors. Of the 53 participants, saliva
samples were taken before and after the stressors from 15 (6 male)
participants, ages 21-45 (mean 27), for the determination of cortisol
levels. Cortisol reactivity was measured by subtracting baseline
cortisol levels from post-stressor task levels.
Results supported a relationship between self-esteem and
depression (r = .57, p = .025). Results did not support a
relationship between self-esteem and cortisol reactivity, indicating
cortisol reactivity is not acting as a mediating variable. In order to
test whether cortisol reactivity functions as a moderating variable, a
two-way ANOVA was performed. Results indicated significant main
effects for self-esteem (p =
.006) and cortisol reactivity (p = .007). Results also indicated a
significant interaction (p = .012), whereby depression is highest in
those exhibiting a combination of low self-esteem and high cortisol
reactivity.
In conclusion, a psychobiological explanation for depression may
exist, such that individuals with lower self-esteem and high cortisol
reactivity are at the greatest risk for depressive symptomatology.
Coping-related drinking in high anxiety sensitive individuals
Alan MacDonald and Sherry Stewart
Dalhousie University
The present study evaluated Sher's (1987) stress- response dampening
(SRD) theory to explain the increased sensitivity of high anxiety
sensitive (AS) subjects to alcohol- induced SRD effects compared to low
AS controls. High and low AS subjects were divided into alcohol and
placebo groups and participated in a hyperventilation challenge known
to induce physiological symptoms feared by high AS subjects (Donnell &
McNally, 1989). Reactivity was measured using affective, cognitive and
somatic self-report scales and measures of heart rate (HR), blood
volume pulse (BVP) and skin conductance level (SCL). Preliminary
analyses suggest that high AS placebo subjects showed greater
reactivity to the challenge on affective and cognitive measures than
low AS placebo subjects. Furthermore, both high and low AS alcohol
subjects showed less reactivity on somatic self- report measures
compared to placebo subjects. However, on affective and cognitive
measures, the strongest reductions in reactivity were seen in high AS
subjects, suggesting that alcohol may be reinforcing for high AS
subjects by eliminating their tendency to become fearful and
catastrophize about aversive experiences. Based on previous
psychophysiological findings (Stewart & Pihl, 1994) and preliminary
analyses, high AS placebo subjects were expected to show greater SCL
reactivity in response to the hyperventilation challenge than low AS
placebo subjects. In addition, all subjects receiving alcohol were
expected to show less SCL reactivity compared to placebo subjects, with
the strongest alcohol-induced SCL reductions expected for high AS
subjects. The results are discussed in terms of the theoretical links
between AS and psychophysiological vs. subjective-emotional responses
to stress.
Is a frontal positive slow wave in the ERP specific for emotion-focused
processing?
Stefanie Maier1, Oliver Diedrich2, Gabriele Becker1, Ewald Naumann1, and
Dieter Bartussek1
1University of Trier, 2University of Tuebingen
Emotional slides elicited a frontal positive slow wave in the ERP with
larger amplitude for an emotion-focussed processing group than for a
structural processing group. This effect was interpreted as a
consequence of the activation of specific neuronal structures when
subjects attend to the emotional content of the stimuli. The aim of the
present study was to show whether the emotion-focussed processing of
neutral slides elicits a frontal positive slow wave as well.
Therefore, ERPs were recorded from subjects watching either emotionally
neutral or negative slides (presented for 6-7.5 sec). Four experimental
groups were examined. Each subject performed three phases with 23
slides each: In phase 1 all subjects rated neutral slides along the
cognitive dimensions "shape" and "size", in phase 3 all subjects rated
negative slides along the emotional dimensions "arousal" and
"valence". In phase 2 the different groups rated either neutral or
negative slides along either the cognitive or the emotional dimensions.
EEG was recorded from F3, C3, P3, Fz, Cz, Pz, F4 C4, P4 from 300 ms
before until 4500 ms after stimulus onset. The results show that the
frontal positive slow wave is elicited during emotion-focusssed
processing of neutral slides, but also during cognitive processing of
negative and neutral slides. Thus the frontal positive slow wave seems
not specific for emotion-focussed processing of emotional slides. A
reanalysis of the experiment shows that other features than the
emotional content of the slides have an influence on the ERPs as well.
Supported by Deutsche Forschungsgemeinschaft.
A comparison of the Schandry and Method of Constant Stimuli procedures
for assessing heartbeat perception
Jennifer Mailloux and Jasper Brener
State University of New York at Stony Brook
Although Schandry's heartbeat counting task is widely used to assess
the ability to perceive cardiac sensations, performance on this task
may be determined by processes other than sensitivity to cardiac
sensations. Subjects may perform well on Schandry's task if they
accurately estimate their heart rate. However, the Method of Constant
Stimuli (MCS) requires that subjects discriminate between stimuli that
are either coincident or delayed with respect to their own heartbeat
sensations and performance on this task is not influenced by the
accuracy of subjects' beliefs about heart rate. This study compared
performance on these tasks. In one session, beliefs about the effects
of posture and exercise on heart rate were assessed before subjects
were required to count their heartbeats while their actual heart rates
were manipulated by changes in posture and exercise. In an attempt to
influence heart rate beliefs, half the subjects (N=40) received
heartbeat-contingent feedback between two presentations of the
heartbeat counting task, whereas the other half received feedback at a
rate 20 percent slower than their actual heart rates. On another
session (MCS), subjects judged the simultaneity of heartbeats and tones
presented at various intervals after the R-wave. Subjects classified
as heartbeat detectors on the MCS procedure were also good at counting
their heartbeats on the Schandry task. Other subjects performed poorly
on MCS but well on Schandry's task. These subjects' may use beliefs
about heart rate to enhance performance on Schandry's task. Supported
by NIH Grant #HL42366 awarded to Jasper Brener.
Blind separation of event-related brain response components
Scott Makeig1,2, Tzyy-Ping Jung1,3, Anthony J. Bell3, Dara Ghahremani3,
and Terrence J.
Sejnowski3
1Naval Health Research Center, San Diego CA; 2University of California
San Diego; 3The Salk
Institute for Biological Studies
The problem of objectively decomposing event-related brain responses
into neurophysiologically meaningful components is a major difficulty
in the evoked response field. Traditional methods of identifying and
measuring response subcomponents based on measuring the amplitudes and
latencies of peak excursions in the waveforms at individual scalp sites
fail when subcomponents overlap substantially, while current source
localization procedures based on fitting single or multiple dipole
models give ambiguous results when source geometry is unknown or
complex. The Independent Component Analysis (ICA) algorithm of Bell
and Sejnowski (1995) is an artificial neural network which maximizes
the overall entropy of a set of non-linearly transformed input vectors
using stochastic gradient ascent, without regard to the physical
locations or configuration of the source generators. Trained on one or
more multichannel electric or magnetic evoked responses, the algorithm
converges on spatial filters which separate the input data into
independent time courses and distinct scalp topographies arising in
multiple, spatially-stationary 'effective brain sources. Response
decompositions produced by the ICA algorithm can be used to measure the
effects of experimental manipulations on individual response
components, even when these are overlapping in time or space.
Typically, response components identified by the algorithm are
recaptured in repeated analyses, regardless of changes in initial
weights, sensor montage, and data length.
I will explain the theory and practice of ICA decomposition and
its differences from PCA, demonstrate results of EEG simulations,
and present applications to EEG and MEG data analysis.
Independent component analaysis of event-related potentials during a
selective attention task.
S. Makeig1,2, L. Anllo-Vento2, P. Jung1,3, A.J. Bell3, T. J. Sejnowski3,
and S. A. Hillyard2.
1Naval Health Research Center; 2University of California San Diego;
3Salk Institute for Biological
Studies, La Jolla, and Howard Hughes Medical Institute.
ERP studies of visual-spatial attention indicate that cortical
processing of stimuli appearing in the attended location is augmented as
early as 80 ms after stimulus onset. However, separation of the multiple
brain processes contributing to the surface-recorded components of ERP
waveforms has proven difficult. Recently, an `infomax' algorithm for the
blind separation of linearly mixed inputs has been devised (Bell and
Sejnowski, 1995) and applied to EEG and ERP analysis (Makeig et al.,
1996). The neural generators of sources are not specified by the
algorithm and may be either physically compact or distributed. Results
of applying this Independent Component Analysis (ICA) algorithm to
single-subject and group-mean ERPs recorded during a visual selective
attention experiment (Anllo-Vento and Hillyard, 1996) suggest that ERP
waveforms represent a sum of overlapping, discrete and time-limited
brain processing events whose amplitudes are modulated by selective
attention without affecting their time course. The source components
identified by the algorithm appear to index independent stages of visual
information processing. Spatial attention operates on early source
components in a manner similar to a sensory gain-control mechanism,
while later components appear to reflect further processing of stimulus
features and feature conjunctions.
Phase of menstrual cycle modulates eye-blink startle potentiation and
magnitude
Rachel Manber, Keith W. Burton, John J. Allen, and Alfred W. Kaszniak
University of Arizona
Emotional modulation of the eye-blink startle reflex was
hypothesized to be sensitive to the emotional changes that often
accompany the premenstrual phase of the menstrual cycle. Seventeen
regularly menstruating healthy young women (ages 18 to 24) were studied
in both midfollicular and late luteal phases. In each session the
magnitude of the eye-blink startle response to positive, neutral, and
negative color slides was measured and the PANAS was administered.
A significant valence effect replicates previous findings when
data from both phases were pooled (p2.3 (p<0.001,uncorrected). Increased activation of the anterior
cingulate (Brodmann's Areas 24 and 32) to infrequent tones was detected
in all four subjects. There was greater fMRI activation in the
anterior cingulate to the infrequent than the frequent tone. The
results suggest that the activation of the anterior cingulate is not
merely related to enhanced generalized attention during the task, and
may have implications for understanding the neural substrates of the
P300 component of the ERP.
EEG characteristics in adolescent males at risk for developing
alcoholism
Amy K. Mertz, Kathryn A. McGuire, Joanna Katsanis, and William G. Iacono
University of Minnesota
It has been well documented that male offspring of alcoholic fathers
are at a higher risk than the general population for developing
alcoholism. In addition, several studies have shown that alcoholics
exhibit unusual EEG characteristics, such as decreased alpha activity
or increased beta activity. However, it is unclear whether these EEG
characteristics are caused by chronic alcohol ingestion, or whether
they pre-date the onset of alcoholism. In order to examine this
possibility, we recorded the resting EEG at Cz referenced to linked
ears, O1-T5, and O2-T6 in three samples of 14- and 15-year-old male
offspring of a) fathers with alcoholism (high-risk; n=37), b) fathers
with alcohol abuse (moderate-risk; n=16), and c) fathers without a
diagnosis of alcoholism (low-risk; n=21). Preliminary analyses of the
data indicated that the high-risk group had significantly lower levels
of alpha activity in the relative and absolute power spectra across all
recording sites relative to those of the low-risk group. Significantly
higher beta activity was also seen in the relative power spectra of
the high- and moderate-risk groups at O2-T6 and of the moderate-risk
group at O1-T5 compared with the low-risk group. These preliminary
findings suggest that certain components of the EEG can function as
possible biological markers for the development of alcoholism.
Sequential changes in the auditory evoked potentials during target
detection
H. J. Michalewski, A. Starr, T. Aguinaldo, and M. Roe
University of California, Irvine
Stimulus sequence effects were examined in auditory detection tasks
(oddball paradigm) that required (1) a button press to targets and (2)
a mental count of the targets. Sequence effects were evaluated by
sorting and averaging single trials to nontargets relative to the
position in the sequence following a target. Normal subjects (n = 13)
listened to a series of 300 tones consisting of 240 nontargets (low
tone) and 60 targets (high tone). Targets occurred randomly in the
sequence with the restriction that the succession of two targets was
not allowed. Tones (250 ms) were presented every 2 sec. Long time
constant (16 sec) recordings were made from midline and lateral scalp
electrode placements. Sweep duration was 1.44 sec and included a 0.76
sec prestimulus period. Nontarget potentials varied in amplitude as a
function of position following the target. A slow prestimulus negative
potential (readiness potential, RP), the N100, and a late slow wave
were smaller to nontargets immediately following the targets than to
nontargets immediately before the targets. The amplitudes of these
components recovered as a linear function of the number of nontargets
in the sequence. P200 amplitude was larger to nontargets following the
target than to nontargets immediately preceding the targets.
Sequential changes (RP, N100) were either absent or reduced in the
count condition; P200 amplitude changed for both press and count
conditions. The results describe the presence of brain activity
subserving response preparation and stimulus processing that are
systematically related to the position of the stimulus in a sequence.
Conditioned gamma band coherences between visual and somatosensory
brain areas after differential classical conditioning of painful stimuli
Wolfgang Miltner1, Matthias Arnold1, Herbert Witte1, and Christoph
Braun2
1Friedrich-Schiller University of Jena, Germany, 2Eberhard-Karls-
University of Tuebingen, Germany
In a recent ERP study (Waschulewski-Floru=DF, H., Miltner, W.,
Brody, S., & Braun, C. (1994). Classical conditioning of pain responses.
International Journal of Neuroscience, 78, 21-32) we demonstrated that
during the last 250 ms of presentation of a visual CS+ reinforced by a
succeeding painful stimulus (UCS) there was a significant increase of
electrical negativity over the receptive field of the stimulated finger
at SI. This negativity did not develop during the last 250 ms of CS-
presentation. Results indicate that occipital brain areas processing the
CS+ communicate with primary somatosensory brain areas processing the
UCS.coherence analysis. 16 subjects participated in the experiment. The
UCS consisted of intracutaneous electrical stimuli. Red and green light
served as CS+ and CS-. UCS was applied during the last 10 ms of CS+
presentation.
EEG data were recorded from 31 electrodes, corrected for artifacts and
then submitted to a coherence procedure (calculated for different
frequency bands) using pairs of electrodes on occipital, primary and
secondary somatosensory areas of both hemispheres. Significant
differences of coherence between CS+ and Cs- conditions were onserved
only within the gamma band with stronger coherences between electrodes
of visual and somatosensory areas during CS+ condition than during CS-
condition. Results indicate that during conditioning brain areas
involved in the information processing of the visual CS+ became rapidly
synchronyzed within the gamma band (i.e, around 40 Hz).
Cortical reorganization in phantom limb pain changes after regional
anesthesia of the amputated limb
P. Montoya, N. Birbaumer, W. Lutzenberger, H. Flor, W. Grodd, K. Unertl,
and W. Larbig
University of Tuebingen
In an earlier paper (Flor et al. 1995), we have demonstrated extensive
reorganization of the primary somatosensory projection areas in phantom
limb pain patients. The magnitude of reorganization correlated 0.95
with the subjective phantom limb pain. Since phantom limb pain persists
usually for years, often for life-time, the plasticity of the
reorganization itself constitutes a critical question for its
therapeutic modification. To test the stability of cortical
reorganization, nine unilateral upper limb amputees were tested before
and after plexus brachialis blockade of the stump. SEPs elicited by
pneumatic stimulation of the 1st and the 5th finger as well as of the
lip (bilateral) were recorded from 60 electrodes. The functional
somatotopic organization of the somatosensory cortex representing the
stimulated regions was obtained using an equivalent current dipole
model and anatomical information provided by individual MRI scans.
Significant group differences were found in the session before
anaesthesia, indicating that in patients with phantom limb pain the
cortical representation of the lip ipsilateral to the amputation side
was significantly more shifted towards the finger region than in
pain-free patients. In addition, a significant reduction in the
magnitude of cortical reorganization was observed in patients without
pain during anaesthesia compared to patients with enduring pain. These
results strongly support the plastic (Hebbian) nature of cortical
reorganization and provide further support for the hypothesis that
plastic changes in amputees are strongly associated with the experience
of phantom limb pain.
Supported by the German Research Society (DFG).
Dissociative experiences, tracking task workload, and EEG
Richard A. Moraga1 and William J. Ray1
1Penn State University
In this study we assess individual differences in a simulated flight
performance task. Thirty individuals scoring high (n=15) or low (n=15)
on the Dissociation Experiences Scale (DES) performed a series of
flight tracking tasks Conditions varied according to flight mode (i.e.,
automatic vs. manual) and task workload (i.e., additional monitoring
tasks). We describe their 17 site EEG using linked ears as reference;
256 HZ sampling rate; .03-35 HZ bandpass; 2 EOG channels for artifact
correction. The EEG data were Fourier analyzed into theta, alpha, beta
and gamma frequency bands and log transformed for ANOVASs (BMDP2V).
EEG task engagement indices, similar to those previously reported (Pope
and Bogart; 1993), using ratios of beta to theta and alpha were also
examined. Main effects involving EEG bands were found for tracking mode
in all bands but theta (e.g., F(1,28)=5.52,p=.03, for gamma activity);
and in all bands for task workload condition (e.g., F(3,84) =26.17,
p 30 min) by 3 to 5 year old children
and college age students have been explained with a model of
"attentional inertia" (Anderson et al., 1987; Burns & Anderson, 1993;
Choi & Anderson, 1991). This model posits that attention to a visual
stimulus increases over the course of a fixation. The current study
examined fixation durations and HR changes in young infants (3 to 6
months) to determine if the attentional inertia model was applicable to
infants.
Infants at 14, 20 and 26 weeks of age (N = 5 per age) were
presented a Sesame Street movie ("Follow That Bird") in session 1,
and computer-generated patterned stimuli accompanied by abstract sounds
in session 2. The 20 min sessions were videotaped and fixation
direction was judged off-line. HR was recorded during the entire
session.
There was a decreasing conditional probability that a look would
end as fixations became longer. This conditional probability
distribution was consistent with the occurrence of "attentional
inertia" in the fixations. The HR level decreased over the duration of
a fixation and returned to prestimulus level immediately prior to the
fixation offset. The HR change during infants' fixations to extended
visual stimuli suggest an increasing engagement of attention over the
course of a fixation. The pattern of fixations and associated HR
changes provide independent evidence of increasing attentional
engagement with increases in look duration.
Validation of the ambulatory measurement of stroke volume by impedance
cardiography
Harriette Riese, Eco de Geus, and Lorenz van Doornen
Vrije Universiteit, Amsterdam
A detailed insight into the cardiovascular effects of stress in
real-life situations requires the measurement of other variables in
addition to blood pressure and heart rate. Ambulatory impedance
cardiography, as performed by the AMS (Ambulatory Monitoring System)
allows the measurement stroke volume (SV) and cardiac output. At the
present stage of development, however, validation of this technique,
which only recently became available, is needed. The present study had
three goals: 1) to assess the test-retest stability of
impedance-derived SV during laboratory-stress 2) To compare SV levels
during a lab session with ambulatory measurements in comparable field
situations with respect to posture and activity. 3) To compare
ambulatory impedance-derived SV's with SV's as measured with the
Portapres continuous finger blood pressure measurement device.
Thirteen subjects wore both devices during 24 hours. In the morning and
in the afternoon they were exposed to a 5 min serial subtraction task
followed by a 5 min resting period. Test-retest reliability of
impedance-derived SV levels during the resting periods was .63 and
during serial subtraction .86. The comparison of laboratory levels
with comparable periods during the rest of the registration period
showed low correlations overall. For example, lying quietly in the lab
correlated .29 with sleeping. Silent reading in the lab correlated .11
with reading or watching TV at home. The intra-subject correlations
between SV's as measured with the two devices will be presented, and
limitations of ambulatory SV measurements will be discussed.
Problems with small sample sizes in psychophysiological research.
Todd C. Riniolo and Stephen W. Porges
University of Maryland, College Park
Psychophysiological findings, which rely on small samples,
are often insensitive in detecting differences with a small or
medium effect size (ES), and may only achieve statistical
"significance" when an ES estimate is positively biased. Thus,
only ES estimates from small samples that do not accurately index
the population ES achieve significance. Without knowledge of the
entire sampling distribution, biased estimates of the population
ES may be common and spurious findings reported.
A simulation was conducted consisting of 10,000 computer
generated replications creating sampling distributions of ES
estimates from paired t-tests calculated with 12, 25, 50, and 120
degrees of freedom (df). Samples were drawn from a normal
population with a small ES (.2) difference (Cohen, 1988).
Consistent
with the Central Limit Theorem, the mean ES estimate from each
sampling distribution accurately indexed the
.2 ES (independent of df), with a reduction (.31, .21,
.14, .09) in the standard deviation occurring as the df
increased. Using only significant results, the mean of the ES
estimate was inflated (.73, .51, .37, .26) respectively for 12,
25, 50, and 120 df.
Since psychophysiological research often relies on small
samples: 1) ES estimates may be positively biased; 2) single
studies may provide unreliable ES estimates; and 3) true
psychophysiological "laws" may not be detected and unreliable
relations may be reported. Implications from these data suggest
that: 1) psychophysiological data registries be made available via
the internet to provide a full range of results for meta-analyses;
and 2) studies use larger sample sizes.
A paced breathing procedure for the inter- and intraindividual
estimation of cardiac vagal tone
Thomas Ritz, Claus Wagner, and Bernhard Dahme
University of Hamburg, Germany
A method for the control of respiratory modulations of respiratory
sinus arrhythmia (RSA) was tested, together with an interindividual
index of cardiac vagal tone. In the first study 22 asthmatics and 22
healthy subjects performed static muscle contractions of the forearm
and forehead. In the second study 12 healthy subjects were exposed to
forehead temperature stimulations with either cold or warm water bags.
Both experiments were designed to influence vagal activity. Total
respiratory resistance (TRR), respiration, and heart period (HP) were
recorded. RSA was determined by the peak-valley method. Three baseline
measurements of 3 min duration with paced breathing at 8, 13, and 18
cpm were performed. Separate intraindividual regressions against
respiration period were calculated for RSA and RSA normalized for tidal
volume (RSA/VT). Both RSA and RSA/VT revealed highly positive
correlations with respiration period over the paced breathing
frequencies. The slopes of these regressions were tested as
interindividual indices of vagal tone. For asthmatic and healthy
subjects, the slopes correlated positively with baseline HP, RSA, and
an interindividual index of vagal tone proposed by Grossman and Kollai
(1993). In addition, for asthmatic subjects the slopes were positively
correlated with baseline TRR and the Anger/Irritability subscale of the
Asthma Symptom List. To correct for intraindividual modulations of RSA
by respiration, deviations from the predictions of RSA under paced
breathing were calculated. Corrected and/or normalized indices of RSA
proved to be more sensitive than simple RSA for the detection of
experimental effects.
Cortisol as an opportunistic potentiator of blood pressure responses to
laboratory stress
Mark P. Roy 1, Clemens Kirschbaum 2, and Andrew Steptoe 3
1 Penn State University, USA; 2 University of Trier, Germany; 3 St.
George's Hospital Medical
School, University of London, UK.
Large cardiovascular stress responses per se are unlikely to be
pathogenic, however a sustained response may directly produce damage,
or increase the window of opportunity for other pathogens. In vitro
and animal studies suggest that cortisol, a stress responsive hormone
in humans, has vasoactive properties, and is a prerequisite in a rat
hypertension model. Hypothesis: Concurrent large cardiovascular and
cortisol reactivity will be associated with more sustained blood
pressure (BP) increases, than isolated large cardiovascular reactors.
90 male probationary firefighters (Age:19-31) took part in a laboratory
session. After 1 hour of habituation, the session consisted of seven
sampling trials (10 minute): baseline; mental arithmetic; inter-task
recovery; speech task; and three recovery trials. Within trial BP & HR
were monitored beat to beat, and saliva was sampled during each trial
for cortisol determination. For each measure (SBP, DBP, HR and
Cortisol), large trial main effects were found (p<0.0001). Group by
trial interaction effects (SBP, DBP and HR p<0.0001; Cortisol,
p<0.001), suggested that cardiovascular reactivity was independent of
baseline levels, whilst cortisol reactivity was baseline dependent.
Chi2 analyses showed no association between being a cardiovascular
reactor and a cortisol reactor. The impact of coincidental
cardiovascular and cortisol reactivity was analyzed by grouping on
reactivity, the groups being: concurrent reactors; cardiovascular
reactors; cortisol reactors; and non-reactors. Significant interaction
effects (SBP & DBP, p<0.0001), were associated with the largest and
most sustained BP responses being in the concurrent reactor group.
Results are discussed in terms of underlying mechanisms, and the
significance for reactivity in hypertensive pathophysiology.
How the cookie crumbles: A lab study study of affective distress,
dietary restraint, and cardiovascular activation
Thomas Rutledge and Wolfgang Linden
The University of British Columbia
We adopted an affective distress-induction procedure from the
cardiovascular psychophysiology paradigm to test the relationship
between stress and eating behavior in a female college population.
Participants were assigned to one of three conditions, an
experimental-inhibition (EI), experimental-expression (EE), or control
group (C), in order to manipulate the opportunity to express negative
affect, and to provide a means of assessing the impact of differential
stress recovery upon eating behavior. All groups responded to a 12-min
lab challenge that involved three active coping tasks and groups EI and
EE were additionally repeatedly interrupted in an attempt to augment
distress. Expression of distress during the 12-min recovery period
was either encouraged (EE) or discouraged (EI). Measures of dietary
restraint and positive and negative affect were included to complement
blood pressure and heart rate indices.
The analysis of food consumption data showed that physiological
stress was the strongest predictor of post-stress eating
behavior showing less eating with greater concomitant arousal.
Self-reported affect failed to correlate with either food consumption
or physiological stress. Dietary restraint also proved to be a
reliable predictor of food consumption, even after controlling for
physiological stress. Finally, an examination of physiological
recovery data revealed that those subjects who were permitted to
express their affect showed a more rapid heart rate recovery relative
to those prevented from diffusing their emotions. Variations in eating
behavior were not associated with differential recovery however.
Hemisphere differences and aware/ unaware processes in classical
conditioning.
Sara Saban, Kjell Morten Stormark, Dag Hammerborg, and Kenneth Hugdahl
University of Bergen
The present experiment investigated effects of brain asymmetry in
classical conditioning, with aware/ unaware modes of extinction.
Subjects were conditioned to one of two consonant-vowel syllables as
the CS+, which was paired with an aversive noise. The other syllable
(CS-) was never paired with the unconditioned noise. The syllables
were presented binaurally during acquisition. The conditioned
acquisition phase thus followed a standard conditioned discrimination
procedure. During the extinction, the two CS syllables were presented
in one ear only, either left or right, with one of four new syllables
simultaneously presented in the other ear on each trial. Thus, the
extinction phase used a dichotic listening procedure, which allows for
probing one cerebral hemisphere at a time with the CS+ and the CS-. In
addition, half the subjects were attending the right ear stimuli (left
hemisphere), while the other half were attending the left ear stimuli
(right hemisphere). All physical parameters of the stimuli were the
same for both groups during all phases of the experiment, except for
the left versus right ear attention instructions during the extinction
phase. Skin conductance responses (SCRs) were recorded, and the
results showed that conditioning occured in both =93groups=94 during
acquisition, indicated by a significant difference between responses to
the CS+ and CS-. During the extinction phase, both groups showed
evidence of conditioning in the attended condition. However, there was
a significant laterality effect for the unattended condition, with
larger responses to the CS+ compared to the CS-, only for the left
hemisphere group.
Relations between foreperiod muscle tension and anticipatory heart
rate.
Dean Sabatinelli, Glen Griffin, and W. Keith Berg
University of Florida
In a forewarned reaction-time study, Haagh and Brunia
(Electroencephalography and clinical Neurophysiology, 1985, 61, 30-39)
separated subjects into two groups according to the presence or
absence of spontaneous soleus muscle tension during the foreperiod.
Group differences in measures of cortical anticipation were reported.
To examine the generality of these findings, we similarly divided
subjects based on forearm EMG tension during the foreperiod and
examined how this relates to a cardiovascular measure of
anticipation.
This relationship was examined in two separate choice reaction-
time studies. Subjects were cued 6 s in advance by a visual warning
stimulus, and quickly responded to the visual Go stimulus by
compressing a device with their entire hand. In the first study, EMG
data beginning 2s prior to the Go stimulus onset was utilized to
separate subjects into two groups according to each subject's level of
pre-response EMG tension. The tense group showed 72% larger
anticipatory HR decelerations than the relaxed group. In the second
study, data collected over the entire foreperiod replicated the HR
findings of the first study, and showed that the EMG tension increases
began immediately after the onset of the warning stimulus. Subjects
were separable into increasing-tension and relaxed groups, with the
tense group showing 50% larger HR anticipatory decelerations.
These data, together with those of Haagh and Brunia (1985),
suggest that information on muscle tension available soon after
warning stimulus onset can predict changes in anticipatory components
of electrocortical and cardiovascular responding several seconds
thereafter.
Wait and see: Aversion and activation in anticipation and perception.
Dean Sabatinelli, Margaret M. Bradley, Bruce N. Cuthbert, and Peter J.
Lang
University of Florida
Anticipation and perception of unpleasant events have been found
to be associated with potentiated startle responses. This study
investigates the separate roles of aversiveness and activation in
mediating these effects. Male and female subjects high in
self-reported snake fear first anticipated, and then perceived,
pictures of snakes. To examine the role of arousal, erotic and neutral
(household objects) pictures were also presented. During a 6 s
anticipation period, a light cue signalled the category of an upcoming
picture, which was then presented for 6 s. Startle blinks were
elicited by acoustic probes in either the anticipation or perception
periods on each trial. If aversiveness mediates potentiated startle in
both anticipation and perception, subjects high in snake fear were
expected to respond with greater startle magnitude when processing
snake pictures, compared to low fear subjects.
Results indicated that snake-fear subjects showed significantly
larger startle responses when viewing pictures of snakes compared to
low fear subjects, whereas the groups did not differ in their startle
responses when viewing erotic (or neutral) materials. During
anticipation of snake pictures, however, group differences were absent.
Across all subjects, startle blinks during anticipation were reliably
larger for both erotic and aversive pictures, compared to neutral
stimuli. These data support the hypothesis that startle modulation in
perception is related to picture aversiveness. On the other hand, in
light-cued anticipation, acoustic startle responses are potentiated by
the arousing quality of the anticipated stimulus.
Startle responding to alcohol cues among alcoholics
Michael E. Saladin, David J. Drobes, Julian M. Libet, and Raymond F.
Anton
Medical University of South Carolina
Previous research has convincingly demonstrated that the eyeblink
component of the startle reflex elicited by a sudden, intense stimulus
is positively related to the aversiveness of foreground stimuli. Based
on these findings, it might be expected that appetitive alcohol cues
should inhibit startle responses, particularly among alcoholics. This
study investigated the effects of alcohol cues on startle responding
among alcoholics.
Fifty alcoholics were exposed to two each of alcohol, water, and
non-cue trials, each lasting for three minutes. Alcohol trials
consisted of exposure to the sight and smell of the subject's preferred
alcoholic beverage. The order of alcohol and water trials was
counterblanced across subjects, and all of these trials followed the
non-cue trials. During one trial of each type, six acoustic startle
probes were presented (50 ms, 115 dB) at random intervals. The
resulting eyeblink was measured along the orbicularis oculi region
under the left eye. The other trial of each type involved salivary
measurement (a traditional measure of alcohol cue reactivity), as well
as self-reported craving and affect.
Results indicated enhanced startle responding during the alcohol
trials, relative to water and non-cue conditions. Subject ratings
suggested that alcohol trials were also associated with enhanced
alcohol cravings, and that this experience was highly aversive. These
findings demonstrate that exposure to appetitive cues may elicit a
negative emotional response under certain conditions. Potential
explanations for this pattern of response will be discussed, as well as
directions for further research.
Midline P3 amplitude interactions in schizophrenia and mania
Dean F. Salisbury, Iris A. Fischer, Martha E. Shenton, Andrea R.
Sherwood, Paola Mazzoni, and
Robert W. McCarley
Harvard Medical School/McLean Hospital
P3 was recorded from 29 schizophrenic, 17 manic, and 24 'normal'
control subjects, as they silently counted target tones (1.5 kHz, 97
dB, 15%) interspersed among standard tones (1 kHz, 97 dB) while
presented against 70 dB white noise. P3 amplitude was measured from
target waveforms as the mean voltage from 300 to 400 ms at Fz, Cz, and
Pz. Repeated measures ANOVA revealed significant midline P3 differences
for groups (F(2,67) =15.5, p 5 per cent or
new wall motion abnormality. Patients who developed ischemia had
significantly larger diastolic blood pressure responses to the speech
task than non-ischemic patients (means (SEs) = 31.2 (4.0) mmHg and 19.8
(3.1) mmHg, respectively, p 1000 ms) that were presented
foveally. In pilot research, we developed a set of simple pictorial
stimuli for which subjects could accurately make evaluative
(positive/negative) and nonevaluative (animal/nonanimal) judgments when
the stimuli were presented for 180 ms in right or left hemifields. We
subsequently used these stimuli to examine whether differences in
evaluative and nonevaluative categorization processes could be indexed
using ERPS when stimuli were presented just above sensory threshold
levels to nonfoveal as well as foveal regions. Fourteen subjects were
exposed to sequences of five stimuli and performed a dichotomous
evaluative or nonevaluative categorization task. Categorization
inconsistency was varied by embedding either a negative picture in a
sequence of neutral pictures (evaluative task instructions) or a
picture of an animal in a sequence of nonanimal pictures (nonevaluative
task instructions). These target stimuli were presented foveally or in
the left or right hemifield whereas all remaining pictures were
presented foveally. Despite the use of stimulus presentations so brief
that the lateralized presentations appeared outside of the spotlight of
attention, results replicated prior research showing a larger P300 over
centroparietal regions to categorically inconsistent than consistent
stimuli. Implications for investigating the neural substrates of
evaluative processing are discussed.
Modulation of the potentiated startle response: The role of temperament
Nancy Snidman and Jerome Kagan
Harvard University
The EMG startle response to an acoustic probe can be potentiated by
the threat of an aversive stimulus. The role of temperamental
differences in modulating this response was examined in children
categorized by behavioral reactivity during infancy and early
childhood. One group was selected to be high in behavioral reactivity
at 4 months of age and behaviorally inhibited at 14 months and 4 years
of age, while another group did not show this consistent pattern. As
part of a laboratory battery at 6 years of age, eyeblink startle
responses were elicited by an acoustic probe under threat and no threat
conditions. A green light signaled trials during which an aversive
stimulus, an airpuff (60psi), delivered to the throat at the level of
the larynx, might be presented, and no light trials during which an
airpuff would never occur. On each trial, a 95dB, 50-ms burst of white
noise was presented binaurally through headphones and EMG activity of
the m.orbicularis oculi was measured. Preliminary data on the first 10
subjects revealed that the high reactive/inhibited children showed
greater blink magnitude to the acoustic probe during the threat
condition than the non-threat condition compared with other children.
The results suggest that subjects categorized as high reactive in
infancy and behaviorally inhibited in subsequent years may have a lower
threshold of arousal in limbic structures that could explain their
behavior in the laboratory and their potentiated startle response to a
threat condition.
Lateralized control of inotropic and chronotropic cardiac reactivity to
stress
Kathleen Soderlund1, Beth Colaluca1, Stefan Wiens2, Sarah Reiff2, Tamera
Schneider2, and Robert
M. Kelsey2
1University of North Texas, 2State University of New York at Stony Brook
Sympathetic nervous system control of the heart is apparently
lateralized, with the left cardiac sympathetic nerve (CSN)
predominating over inotropic performance and the right CSN
predominating over chronotropic performance. The relationship of CSN
lateralization to central hemispheric lateralization (e.g.,
contralateral, ipsilateral, unilateral, bilateral) is less clear. This
relationship was explored by requiring subjects to tap their left index
finger (right hemisphere activation) or right index finger (left
hemisphere activation) throughout a 1-min vocal mental arithmetic
task. Preejection period (PEP), an inotropic index, and heart period
(HP), a chronotropic index, were recorded from 50 undergraduate women
who were right-handed according to the Edinburgh handedness
questionnaire. All subjects completed an initial 10-min baseline
period, a 5-min mental arithmetic training task, a second 5-min
baseline period, and a 1-min mental arithmetic test task. For the test
task, subjects were randomly assigned to either a left tap group
(n=17), a right tap group (n=16), or a no tap control group (n=17).
Left and right tap groups did not differ significantly in tapping
frequency (p>.75). A multivariate analysis of PEP and HP reactivity
(changes from pretask baseline) during the test task, using initial PEP
and HP reactivity to the training task as covariates, revealed a
significant effect of tapping condition (p .95, standing: .70< r >.80). Resul ts indicated good
postural stability for all cardiovascular measures with correl ations
being slightly larger for SBP as compared to HR and DBP (HR: r= .72 and
. 72, SBP: r= .80 and .82, DBP= r=.71 and .76). These data lend
support for the notion that cardiovascular response to FCPS is a stable
individual difference across postural contexts.
EEG maturation and the development of ocular artifacts
Riek Somsen and Bert van Beek
University of Amsterdam
The majority of EEG artifact treatment studies have paid little
attention to the specific problems of young children. In children the
amount of ocular artifact in the EEG decreases with age. Until age 6
often more than 75% of the EEG records is contaminated with eye and
head movements. The EEG frequency window which is most susceptible to
artifacts from 0 to 10 Hz also shows the greatest maturational decrease
between 0 to 10 years. Finally, in children the physical distance
between electrodes is very small. Both the EOG and EEG electrodes
record eye movements and cerebral activity. Hence, these artifacts are
difficult to distinguish from cerebral EEG. We used a specifically
designed EEG processing program (eEG_ANalysis). The children were
between 5 and 12 years (n=142). The effects of different artifact
treatments in relation to age were studied. The conditions were: 1)
uncorrected EEG. 2) EOG-EEG transfer correction. 3) selection of EEG
epochs that were free of blinks and head muscle artifacts. 4) selection
of EOG epochs with minimal power between 1-6 Hz (minimal horizontal eye
movements). 5) 3 and 4 combined.
Correction reduced EEG power at all scalp locations and frequency
bands and removed more high frequency power with increasing age. The
three selection conditions yielded much lesser and highly selective
reduction of spectral power at the frontal and central locations, only
for the Delta and Theta bands. Blink selection was relatively stronger
in the youngest, while removal of horizontal eye artifacts was stronger
in the oldest children.
The development of selective attention as indexed by heart rate
Riek Somsen, Maurits van der Molen, Bert van Beek, Monique Geers, Saar
Langkamp, Nienke Stark.
University of Amsterdam
Between and within channel auditory selective attention was
examined in two groups of children of 7 and 11 years old by presenting
tone pips of different pitch randomly to opposite ears. Some of the
pips had a slightly higher pitch. The children were instructed to count
the deviant pips at one ear and to ignore all pips at the other ear.
The amount of frequent pips which preceded a rare was varied. Series of
frequents which ended with a rare consisted of 4, 8, and 12 pips.
Cardiac interbeat intervals were sampled twice: one time for the
attended tone pips and one time for the non-attended tone pips. The
cardiac interbeat intervals responded differently to the attended tone
pips. Initially the heart was slowed when the rare was presented,
followed by increased heart rate when the subject was counting. When
adult subjects are waiting for the rare tone to occur, their heart rate
is slowing until the deviant stimulus is detected which is followed by
heart rate speeding. This expectancy response was absent in the youngest
children and was present in the older children only for the series of 4
and 8 pips. In the non-attended series no anticipatory deceleration
occurred. The youngest children made relatively more counting errors.
These results indicated that the developmental rates of the three
selective attention functions was not the same: tone discrimination and
channel separation were reasonably developed in both groups, while the
expectancy response was absent in the youngest children, while it was
present for relatively tone series in the 12 year olds.
Visuospatial attention effects on brainstem reflexes and cortical
event-related potentials
Douglas C. Sonnenberg, Kathy A. Low, and Steven A. Hackley
University of Missouri-Columbia
Previous research has shown that selective attention can enhance the
ability of a weak visual prestimulus to inhibit the blink reflex to a
subsequent startle stimulus. We studied this phenomenon in 20 young
adults, with concurrent recordings of visual evoked potentials, the
postauricular reflex, and behavioral indices of perceptual sensitivity
(d') and criterion (B).
Subjects judged the duration (300 or 500 ms) of the illumination of
one of two diodes, which were located 25 degrees to the left and right
of fixation. A centrally located arrow either correctly or incorrectly
precued the location of that target: p(valid) = .80; p(invalid) = .20.
Event-related potentials were recorded at O1' and O2' sites on such
trials. On other trials, an intense noise burst followed the target at
an asynchrony of 150 ms. The ability of the target to produce prepulse
inhibition of the eye-blink and pinna-flexion components of acoustic
startle was measured.
Prepulse inhibition of startle-blink was reliably augmented on
valid as compared to invalid trials. Similarly, the cortical P1 and N1
potentials evoked by the target/prepulse stimuli were enhanced by
spatially focused attention. (Postauricular reflexes and task
performance measures have not yet been analyzed.). Reflex modulation
and event-related potential data provide converging evidence that
spatially selective attention can influence low-level visual pathways.
Supported by National Institutes of Health grant MH47746 to SAH.
A simulation study of single-trial ERP latency estimation methods
Kevin M. Spencer and Emanuel Donchin
University of Illinois at Urbana-Champaign
One of the key assumptions underlying signal averaging is that each
event triggers a time locked response that has precisely the same
temporal pattern across trials. This assumption is violated if the
latency of ERP components vary from trial to trial. Such "latency
jitter" distorts the shape and amplitude of the ERP. Indeed, it is
improper to compare the amplitudes of ERPs computed over epochs with
varying degrees of latency jitter.
The effects of latency jitter may be counteracted by applying a
method that estimates the latency of the component in each trial.
With these estimates, the trials are re-aligned to compute a new
average. A critical aspect of latency jitter correction is the method
used to estimate single-trial latencies. Many decisions need to be
made when such a latency estimation method is applied, and the
implications of these decisions under different experimental conditions
are quite variable.
We report here a simulation study in which the accuracy of several
latency estimation methods was assessed. A data set of 15 "subjects"
was simulated, each subject's data consisting of 50 trials with a
component of fixed amplitude embedded in Gaussian noise. Five latency
estimation algorithms were tested: peak-picking, cross-covariance,
cross-correlation, cross-covariance with wavelet transform, and
cross-correlation with wavelet transform. We varied in the simulation
the following factors: signal-to-noise ratio, filter cutoff frequency,
template width, and number of wavelet coefficients. Complex
interactions were observed among these factors, and will be described
in detail.
Receiver operating characteristic analysis of psychophysiological
indices in schizophrenia
Scott R. Sponheim1, Sean M. Nugent1, William G. Iacono2, and John W.
Ficken3
1Veterans Affairs Medical Center, Minneapolis, Minnesota, 2University of
Minnesota, 3National
Computer Systems
Psychophysiological indices have been used to characterize biological
abnormalities associated with schizophrenia; however, few studies have
examined the diagnostic utility of these indices. We employed receiver
operating characteric (ROC) analyses to determine the extent to which
psychophysiological indices discriminate between schizophrenia patients
and normal controls.
Subjects completed a battery of measures on which schizophrenia
patients have been shown to exhibit abnormalities. Ocular motor
functioning was assessed during a smooth-pursuit eyetracking task (20
cycles at .4 Hz). Electrodermal activation was measured during a
habituation task consisting of soft (85 dB) and loud (105 dB) tones.
The visibility of the capillary plexus at the base of the nailfolds was
measured using Maricq's Scale of Plexus Visibility (Maricq, 1970).
Electroencephalograms (EEGs) were collected from subjects in a resting
state.
Univariate ROC analyses yielded area under the curve (AUC)
values that were greatest for indices of ocular motor function
and nailfold plexus visibility. AUC values for indices of
electrodermal activation and EEG low-frequency and alpha band power
yielded AUC values that were greater than chance group assignments but
lower than AUC values for indices of ocular motor functioning and
nailfold plexus visibility. Multivariate analyses revealed that
measures of ocular motor functioning and nailfold plexus visibility
together yielded a greater AUC value than either measure alone.
Indices of electrodermal activation and EEG low-frequency and alpha
band power failed to add significantly to the AUC value of ocular motor
functioning and nailfold plexus visibility taken together.
Context- and intensity-effects on psychophysiological emotion responses
Gerhard Stemmler
University of Marburg
Autonomic activity and self-reports of emotion were collected from
N=3D158 female Ss under a crossed Group (Ss blind or informed about
impending emotion inductions) x Emotion (fear, anger) x Emotion
Intensity (high, medium) x Emotion Induction Context ("real-life",
imagery) design,with Context presented in two separate sessions. The
real-life context per se elicited larger autonomic and subjective
responses than imagery. Blind compared to preinformed Ss exhibited
much larger physiological responses in the real-life context, but not
during imagery. Self-reported emotions, however, were similarly large
in both contexts. During imagery, autonomic activity of fear and anger
was practically indiscriminable, but highly differentiated during
real-life inductions. Intensity influenced several autonomic variables.
Results are discussed in terms of current theorizing about "basic"
emotions and emotional specificity.
Is the EGG a marker for infant colic? Results from a prospective study
Cynthia Stifter, Dave Zelis, Jane Mihailoff, and Ken Koch
Pennsylvania State University
Several hypotheses exist regarding the etiology of colic. What is
undebatable is that infants who have colic appear to be experiencing
discomfort that seems tocenter around the GI tract. Studies of adult's
gastric myoelectrical activity (EGG) suggest that dysrhythmia or
tachygastria is associated with nausea, vomiting, and motion sickness.
To examine whether infants with colic present with different gastric
myoelectrical activity, a prospective study was conducted in which
EGG's were recorded at 2 weeks of age before the onset of colic, and at
6 weeks of age during the period colic emerges. Attempts were also
made to record EGG at 8 weeks of age during a colic bout. EGG's were
recorded postprandially for 30 minutes using a portable computer.
Special procedures designed to detect and remove movement artifact were
applied to the data. Spectral densities in the following frequencies
were calculated: bradygastric (1-2.5cpm), normal (2.5-3.75cpm),
tachygastric (3.75-10cpm), and duodenal (10-15 cpm). Recordings were
available for 61 two week olds and 68 six week olds. Colic was
identified in 7 of the infants. Results revealed that at 2 weeks colic
and noncolic infants exhibited significantly different EGG's. Infants
with colic had less bradygastria and more tachygastria. At 6 weeks,
only the bradygastric range was different for the two groups. Only 1
colic infant was recorded during a colic bout but he exhibited large
amounts of tachygastria compared to the other frequencies. The results
of the present study suggest that EGG may be a physiological marker for
the identification of infants susceptible to colic.
Ouch, that hurts! Blood pressure and heart rate responses to a dental
exam
Evelyn R. Sullivan, Bruce N. Cuthbert, Katherine Karpinia, Arthur Hefti,
and Peter J. Lang.
University of Florida
This study is part of an ongoing project investigating the
relationship between psychophysiological responses to stressful and
potentially fear-provoking situations in both real-life settings and in
corresponding laboratory representations. In the present study,
questionnaire and interview measures were used to assign 35 college
students to either low, medium, or high dental fear groups. Subjects
underwent a periodontal exam including a manual gingival exam and an
invasive examination with an automated probe (Florida Probe) to measure
gum attachment and pocket depth. Systolic (SBP) and diastolic blood
pressure (DBP), and HR were measured before, during, and after each
procedure.
Overall, analyses showed highly significant SBP and DBP
increases from an initial resting baseline for all exam
components. BP increased during the gingival exam, although not
significantly relative to immediate pre-gingival exam levels. BP
levels increased significantly in anticipation of the probe procedure
and continued to rise during the probe exam, finally plateauing during
the final recovery period. Compared to low fear subjects, medium fear
subjects showed significantly larger SBP responses to the probe, with
high fear subjects falling in between the other two groups; these
increases were maintained during recovery. No fear group differences
were present for HR. Interestingly, HR levels did not change from
baseline during anticipatory periods, but did drop significantly during
the gingival exam and probe procedures, remaining below baseline levels
during recovery. This pattern of results suggests a passive behavioral
set to the procedures in all groups, with BP increases likely modulated
by peripheral vasoconstriction.
Resting anterior EEG asymmetry predicts affect-related information
processing
Steven K. Sutton1, Richard J. Davidson1, and Gregory M. Rogers2
1University of Wisconsin in Madison, 2Northwestern University
Previous research has shown that individuals with greater left (right)
anterior resting EEG asymmetry experience more positive (negative)
affect and behavioral approach (inhibition). Using these data, it was
predicted that this brain activity measure would be related to the
processing of stimuli that varied in affective tone. 82 undergraduates
(44 F) completed two resting EEG sessions between 4 and 28 months prior
to performing a repeated, simple choice task where two word-pairs were
presented simultaneously. The subject chose the word-pair that "went
together best." Word-pairs were previously categorized as either
negative (e.g., criminal-prison), neutral (e.g., book-cover), or
positive (e.g., won-victory); with 48 exemplars in each category.
Subjects responded to a quasi-random sequence of negative-neutral,
negative-positive, and neutral-positive comparisons. Individuals with
greater left anterior (FpF1/FpF2) resting EEG asymmetry were more
likely to select positive word-pairs (r = .25, p = .02); whereas
individuals with more right anterior resting EEG activity showed a
tendency to select negative word-pairs (r =
.20, p < .07). Resting EEG asymmetry from central and posterior
regions did not predict word-pair selection (r's ranged from .06 to
-.11, p's >.31). Furthermore, the 26 individuals exhibiting relatively
stable anterior EEG asymmetry showed a stronger significant relation
between left anterior EEG asymmetry and the selection of positive word-
pairs (r= .40, p = .04). These data suggest that anterior brain regions
are related to the processing of affect-related stimuli.
ERP evidence for effects of imageability and semantic distance in word
processing.
Tamara Swaab1, Kathleen Baynes1, and Robert T. Knight1,2
1Center for Neuroscience, UC Davis, 2VAMC Martinez
In a previous study we found that non-aphasic right hemisphere (RH)
patients failed to show a modulation of the N400 to non- associatively
related target words that were from the same semantic category
(Hagoort, Brown, & Swaab, in press). The same RH patients showed
relatively normal associative N400 priming effects. This result might
indicate that the RH is important in the processing of distantly
related words (coarse semantic coding). However, the words that were
used in the semantic condition of this study were highly imageable. It
has been proposed that the RH plays a role in the processing of highly
imageable words. In the present study, we examined the separate
contributions of semantic distance and imageability on the amplitude of
the N400. Four stimulus lists of 80 word pairs were constructed, half
the pairs were unrelated. Two lists contained word pairs that had
strong associative relations, and two lists contained 40
non-associatively related word pairs that were from the same semantic
category. One of the associative lists and one of the semantic lists
contained highly imageable words, the other two lists contained weakly
imageable words. The 320 word pairs were presented auditorily, in
random order. The results showed that the distance of the semantic
relation and the degree of imageability both influenced the size and
the topographic distribution of the N400 effects. These results will be
evaluated in terms of dual-coding theory versus context-availability
theory. Possible implications for the role of the RH in word processing
will be discussed.
When do we dream? Comparison of dreams at sleep onset between REM and
nREM periods
Tomoka Takeuchi1, Akio Miyasita1, Maki Inugami1, and Yukari Yamamoto2
1Tokyo Metropolitan Institute for Neurosciences, 2Waseda University
No one can answer conclusively whether REM dreams differ from NREM
dreams in quantitative and qualitative terms. In comparison of dreams
between REM and NREM periods, many researchers failed to control dreams
elicitation and/or analysis, in terms of a)uncontrol of the sleep
length or stages before the appearance of REM or NREM (stage 2)
periods, and b)contingent of extraneous variables ascribed to
experimenters or subjects in sampling or analysis of data. Our
experiment achieved control of these problems. By a sleep interruption
technique (Miyasita et al., 1989, Electroenceph. clin. Neurophysiology,
73, 107-116.), we elicited sleep onset REM periods(SOREMP). This
technique enabled us to compare dreams at sleep onset between REM and
NREM (stage 2) sleep with their latencies controlled. Further, in
sampling dreams, we had subjects checked on standardized rating scales,
which evaluated properties of dreams. These procedures yielded the
following results. a)Subjects recalled their dreams more from SOREMP
than NREM period. b)The properties of SOREMP dreams differed from NREM
dreams. c)In case the subjects recalled dreams, physiological states
before the appearance of rapid eye movements and of sleep spindles
(K-complex) varied from each other. The results allowed us to
speculate that the process of originating dreams varied between REM and
NREM periods.
Psychopathology and electrodermal response modulation in adolescent
males.
Jeanette Taylor, Scott R. Carlson, William Iacono, David T. Lykken, and
Matt McGue
University of Minnesota
Electrodermal response modulation to an imminent but predictable
aversive stimulus is viewed as adaptive. Given their inability to
reduce the impact of aversive stimuli, poor modulators may experience
problems in certain areas of psychological functioning. We expected
poor modulators to have more psychopathology than good modulators. In
order to test this hypothesis, we assessed the skin conductance
response (SCR) of 150 adolescent males (aged 16-18 years) participating
in the Minnesota Twin Family Study (MTFS). An aversive 90db white
noise blast was presented during five 100 second trials [two
unpredictable (UP) and three predictable (P)]. Response modulation was
indexed with the preception score [100 * (mean UP - mean P) / mean UP],
which reflected the percent increase or decrease in SCR when the blast
is made predictable. From the pool of 150 subjects, three modulation
groups were derived based on their having poor, good, or moderate
preception scores. The Poor group was comprised of subjects with the
lowest 25 preception scores (mean = -43.17), the Good group were those
with the highest 25 scores (mean = 60.25), and the Moderate group
consisted of a random sample of 25 from the middle of the distribution
(mean = 25.50). The three groups were compared on symptom counts of
externalizing, internalizing, and substance use disorders. Good
modulators had significantly fewer symptoms of alcohol use disorders
than both the Moderate and the Poor modulators (who did not differ
significantly). No group differences were found for the other
disorders. These results suggest that good modulation ability may
serve a protective function against alcohol use disorders.
Condition and modality effects on late positive ERP components obtained
during continuous performance tasks
Ayda Tekok-Kilic and David W. Shucard
State University of New York at Buffalo
Previous studies within our laboratory with a visual Continuous
Performance Task (CPT- AX) revealed that scalp-recorded Late Positive
Components (LPCs) were affected by different stimulus sequences or
conditions that were part of the CPT. Following these findings, we have
investigated the effects of condition variables and modality on scalp
recorded LPCs, specifically on the P300 and NoGo P3. Both auditory and
visual versions of the CPT-AX paradigm were presented to right handed
male and female volunteers between 18-35 years in a counterbalanced
order. CPTs were the same in terms of the number of stimuli (n=508),
type of stimuli (letters), and the stimulus sequences. ERPs were
obtained from 12 scalp sites. Here data are reported for midline scalp
sites. The results showed that the amplitude, latency and the scalp
topography of the LPCs (P300 and NoGo P3) changed as a function of the
cognitive processes required by the different stimulus sequences
(conditions) within the CPT task. The NoGo P3 in the A-not-X condition
had the highest amplitude and longest latency in the more anterior
sites. In the target detection condition (A-X), the P300 component
showed a maximum amplitude in the more posterior scalp sites. These
condition-related topographic findings were similar for both auditory
and visual modalities. Results are discussed in terms of both modality
and condition effects on P300.
Analysis of correlated data: Multiple ANOVA's vs. MANOVA
K. A. Thayer and J. F. Thayer
University of Missouri-Columbia
Researchers often collect data on multiple, correlated dependent
variables. For example, multiple cardiovascular variables such as heart
rate, systolic blood pressure, and diastolic blood pressure, or
multiple channels of evoked potential data are collected in a given
experiment. However, these data are often analyzed one variable at a
time using multiple univariate ANOVA's. This approach fails to take
into account the relationships among the dependent variables. This is
particularly important given that subtle effects in the pattern of
response can be masked by this approach. In the present paper we
illustrate the effect of various degrees of correlation among the
dependent variables on the results obtained by multiple ANOVA's versus
MANOVA. Data from two experiments, one involving prenatal exposure to
diethylstilbesterol (DES) in mice, and the other involving a
cardiovascular reactivity paradigm, were analyzed using multiple
ANOVA's and MANOVA. The correlations among the dependent variables were
assessed using Pearson correlations. Results indicate that when the
dependent variables were moderately correlated it was possible to
obtain significant ANOVA's for all of the dependent variables even when
the MANOVA was non-significant. Moreover, when the correlations were
low it was possible to obtain a significant MANOVA without a single
significant univariate test after correction for Type I errors. These
results suggest that MANOVA may provide increased sensitivity to
patterned responses in psychophysiological data and highlight the
different research questions addressed by ANOVA and MANOVA.
Stress responses and motivational systems
Joe Tomaka, Rebecca Palacios-Esquivel, Julie A. Penley, and Sandra D.
Goldsmith
University of Texas at El Paso
This study examined the relationship of stress-related patterns of
cardiovascular reactivity to underlying motivational systems. We
hypothesized that stress responses consisting of high cardiac
reactivity coupled with a decline in systemic vascular resistance
(e.g., challenge, fight or flight, Pattern 1) primarily reflect the
activity of the behavioral activation system (BAS), and that stress
responses consisting of moderate cardiac reactivity coupled with an
increase in systemic vascular resistance (e.g., threat,
vasoconstrictive, Pattern 2) reflect co-activation of behavioral
activation and behavioral inhibition systems (BIS). To activate the
BAS, all participants performed a simple but engaging computer math
task which allowed them to accumulate a very high point score for three
minutes. After three minutes, and in order to co-activate the BIS,
half the subjects began receiving difficult/unsolvable math problems,
causing them to loose all of their previously accumulated points (i.e.,
punishment manipulation). The punishment manipulation, within the
context of previous BAS activation, was expected to represent a state
of co-activation of BAS and BIS systems resulting in a decline in
cardiac activation (heart rate and pre-ejection period), and an
increase in vascular (total peripheral resistance) and electrodermal
(skin resistance) reactions. Results supported the hypotheses for the
cardiac variables (F[1/25] = 9.19, p < .01, for PEP, and F[1/25] =
2.44, p = .08, for HR), but not for the vascular and electrodermal
variables (both ns). The lack of significant effects for TPR may have
been due to the tendency for subjects in general to have strong
positive vascular reactions to the computerized math task.
Event related potentials (ERPs) in Obsessive-Compulsive Disorder (OCD)
during verbal and nonverbal directed-attention tasks
J.P. Towey1,2, G.E. Bruder1, C.E. Tenke1, P. Leite1, R. Fong1, and M.
Leibowitz1
1NYS Psychiatric Institute, 2Mercy College
Our prior studies have found ERP abnormalities in OCD, including
enhanced attention-related negativities to nonverbal sounds suggestive
of overfocused attention and/or hemispheric dysfunction. The current
study investigated both verbal (consonant-vowel) and nonverbal (complex
tone) directed listening tasks in 18 OCD patients and 20 normal
controls. ERPs were recorded from 26 lateral electrodes to monaural
stimuli matched in intensity, duration and repetition rates. After
correcting for eye artifacts, ERPs were submitted to repeated measures
ANOVAs using averages over the latency windows of interest, such as
early (160-250 ms) and late (500-1000 ms) components of
processing negativity (PN). PN components were clearly visible in
difference waveforms for nontarget data (attend minus unattend
conditions). The following Group differences were found: (1) early
PN: Unlike OCD patients, normal controls had larger early PN in the
nonverbal task over right than left hemisphere sites (Group X Condition
X Hemisphere: p=.04). This asymmetry in normals, evident in the
difference waveforms at most sites, may reflect a right hemisphere
advantage for processing complex/musical tones. OCD patients had an
ERP asymmetry in the opposite direction. Patients produced larger
attention-related negativity over left than right hemisphere sites,
consistent with our prior findings for nonverbal stimuli. (2) late
PN: For the verbal task, OCD patients differed from controls in late
PN asymmetry (Group X Condition X Hemisphere: p=.03). The control
group had a larger late PN over left than right hemisphere sites in
this task, possibly due to left hemisphere dominance for
verbal/linguistic processing. There was a small asymmetry in the
opposite direction for OCD patients. These results can be interpreted
as consistent with hypothesized left-hemisphere dysfunction in OCD.
Comparison of CNV amplitude and P300 latency and amplitude in subjects
practicing the Transcendental Meditation Technique for less than 1 year
or more than 8 years.
Frederick Travis
Maharishi University of Management
To investigate possible long term physiological effects of
Transcendental Meditation (TM) practice, 9 subjects, average age 20.7
yrs with 1.1 yrs TM experience, and 12 subjects, average age 20.7 yrs
with 9.3 yrs TM experience, were given a S1-S2 oddball task. The task
comprised a "+" (S1) followed by two single-digit numbers (S2), 2 s
later that subjects were asked to multiply together. If the resultant
product was less than 39, they pressed a left-hand button (standards-
80%); if it was greater than 39, they pressed a right-hand button
(rare-20%). EEG was recorded from Fz, Cz, and Pz, referenced to linked
mastoids. Horizontal EOG was used for artifact rejection.
CNV amplitudes were significantly lower in the group with 9 yrs TM
experience (F(1,19) = 9.6, p = .006). No significant group effects
were seen in P300 latency, P300 amplitude, reaction time or accuracy;
however significant task effects were seen for P3 latency (F(1,19)=4.1,
p=.057) and reaction time (F(1,19)=7.4, p = .016) as expected in an
oddball paradigm. Tecce's two-process model relates CNV amplitude to
attention and arousal. Reduced CNV amplitudes with similar P3
latencies and reaction times to targets might suggest lower tonic
arousal with sustained ability to respond to stimuli. A similar
pattern of lower baselines with quick responses has also been reported
in skin conductance orienting and immune system functioning in subjects
with extensive TM experience.
The MMN is sensitive to perceptual changes in the absence of physical
changes in auditory stimuli
Leonard J. Trejo and Tara M. Johnson
University of Illinois
The Mismatch Negativity (MMN) is believed to arise from comparisons
of deviant auditory stimuli with a sensory memory of a standard
auditory stimulus. In the present study we sought to assess the
influence of higher-order perceptual effects on the MMN, using an
auditory illusion. Our approach was to use a visual-auditory illusion
(the McGurk effect) to make the standard auditory stimulus sound like a
deviant auditory stimulus.
Subjects (n=7, ages 19-25 y, 4 females) watched movies in which an
actor recited a pseudorandom series (4800 trials) of syllables in an
oddball paradigm (e.g., 80% "MA", 10% "KA", 10% illusory "NA"). We
created the illusory syllables by combining visual cues from deviant
stimuli with auditory cues from standards (e.g., KA-lips + MA-sound =
illusory "NA"). Each subject performed the oddball task under two
conditions (MA-KA-NA; BA-GA-DA). All seven subjects reported hearing
the illusion in both conditions. Subjects pressed a button in response
to the auditory deviants (KA, GA) while ERPs were recorded from 30
scalp electrodes, referenced to nose. We computed average ERPs for each
subject x stimulus x condition and measured MMNs in difference waves
(deviant auditory - standard, illusory deviant - standard).
Preliminary analyses suggest that both the physical and illusory
auditory deviants elicit a MMN. This suggests that the MMN generator
does not merely rely on physical stimulus properties in comparing
deviant with standard auditory stimuli. Such information appears to
include higher-order perceptual interactions such as the auditory
illusions of the McGurk effect.
Ethnographic notions of the relationship between physiology and
reported affect in Chinese and European cultures: A test of opposing
predictions
Jeanne L. Tsai and Robert W. Levenson
University of California, Berkeley
Ethnographic studies of Chinese culture lead to two opposing
predictions. Compared to European cultures: (1) stronger Chinese
beliefs in the mind-body relationship predict a stronger relationship
between physiology and self-reported affect; and (2) lesser Chinese
reliance on internal states (and greater reliance on interpersonal
contexts) in determining affect predicts a weaker relationship between
physiology and self-reported affect.
We examined the relationship between autonomic and somatic
physiology and self-reported affect in 48 Chinese American and 50
European American dating couples while they discussed conflicts in
their relationships.
For each cultural group, 20 multiple regressions were conducted
using physiology to predict global and specific affects (overall
affect, extreme positive affect, extreme negative affect, amusement,
anger, anxiety, confusion, contempt, contentment, disgust, excitement,
fear, interest, pain, relief, sadness, satisfaction, shame, surprise,
tension). Physiology was related to specific positive and negative
affects for European Americans (greater autonomic activation related to
less contentment and amusement and more confusion and fear; greater
somatic activity related to more excitement and less confusion). For
Chinese Americans physiology was related to global and specific
negative affects (greater autonomic activation related to more negative
overall affect, extreme negative affect, pain, and sadness; greater
somatic activity related to more positive overall affect and disgust).
Our findings support ethnographic notions of closer mind-body
relationships for Chinese in global affect, but not specific affects.
Opposing notions that Chinese base their affect less on internal states
was supported only by the lack of relationship between physiology and
specific positive affects.
Clinical certification in electrophysiology
Patricia Tueting
University of Chicago
The American Psychiatric Electrophysiology Association (APEA) has
appointed a committee to consider the issue of whether there is a need
to establish a certification mechanism for electrophysiologists engaged
in recording EEG and evoked potentials for the purpose of aiding
clinical judgments on abnormal neurological and behavioral function and
treatment. Electrophysiologists conducting research in clinical
settings are often called upon to contribute to patient care, either as
a part of their clinical research position or in return for
remuneration that can be used to fund research. As with any clinical
activity, it therefore becomes important to establish educational
processes and guidelines to ensure that the research data base is being
used appropriately and that patient safety and quality of care remain
paramount. APEA members are writing position papers on the clinical
application in psychiatry of basic reserach in the areas of: 1)Clinical
and QEEG, 2) Event-related potentials (ERPs), 3) Polysomnography, and
4)Biofeedback. Existing certifying boards in Clinical EEG,
Polysomnography, Biofeedback, Neurophysiological Monitoring (in
operating rooms) are being reviewed by the committee. A list of
certifying programs with summaries of their scope, training, and
eligibility requirements is being compiled.
Event-related potential (ERP) measures of auditory sensory gating:
Pitch and interval parameters
Patricia Tueting1 and Nashaat Boutros2
1University of Chicago and 2Yale University
A systematic decrease in event-related (ERP) amplitude has frequently
been observed as a function of stimulus repetition and shortened time
interval between stimuli. Dynamic processes of neuronal inhibition,
e.g., sensory gating, have been theorized to account for these
findings. In order to investigate parameters related to this proposed
inhibition, ERPs were recorded in three different paradigms in the same
22 healthy normal subjects. Paradigm 1: Long sequences of pairs of
clicks separated by a 500 ms time interval between S1 and S2 were
presented with an interpair interval of 2 s. S1 and S2 were either
identical or non-identical in pitch. Paradigm 2: Long sequences of
two alternative stimuli varying in pitch were randomly presented at
15%/85% relative probability with 2 s between stimuli and at least 4 s
between low probability stimuli. Paradigm 3: Blocks of trials at
varying interstimulus intervals - 0.5 s, 2 s, 4 s, and 8 s were
presented. The gating effect observed in the paired stimulus paradigm
was more pronoucned when the clicks were identical in pitch than when
they were non-identical. For the oddball paradigm, P50 was larger when
elicited by the low probability stimulus, both when the rare stimulus
was lower and when it was higher in pitch than the high probability
stimulus. The counterbalanced design also allowed for an examination
of P50 amplitude across paradigms in the same subjects. The findings
will be discussed in relation to theories of neuronal inhibition,
gating, and cognition.
Expanding the irrelevant-probe technique: Novel auditory probe
sensitivity to workload changes in a complex dual-task paradigm.
Peter Ullsperger1 and Darryl G. Humphrey2
1Bundesanstalt Arbeitsmedizin; 2Wichita State University
The goal of this study was to explore the utility of the novel
auditory probe technique of mental workload estimation in a complex
dual-task paradigm. In addition to a baseline auditory oddball task,
fifteen subjects performed a mental arithmetic task and a gauge
monitoring task in single task and dual task conditions. The
difficulty of the gauge monitoring task was manipulated to give
conditions of graded difficulty. Throughout task performance three
types of auditory stimuli were presented: standards (80%) targets (10%)
and, novel sounds (10%). In the oddball task subjects counted the
number of target stimuli. In the workload tasks the auditory probes
did not require a response. ERPs were recorded from the occurrence of
the tones in both the baseline oddball task and in the three
combinations of the gauge monitoring and arithmetic task. P300
amplitude elicited by targets was sensitive only to the introduction of
the workload tasks. The amplitude of the novelty P3 tended to follow
the gradations of mental workload. To further characterize the novelty
P3 a scalp dipole source analysis was conducted. = In the time range
of novelty P3 two equivalent dipoles were active. Preliminary analyses
suggest these dipoles are differentially sensitive to changes in mental
workload. Obtaining these results in a dual-task environment extends
the realm in which the irrelevant auditory probe technique has
demonstrated sensitivity to changes in mental workload. The use of the
novel probes in addition to the targets and standards allows a finer
grained analysis of this sensitivity.
Accessory stimulus (prepulse) effects on the lateralized motor
readiness potential.
Fernando Valle-Inclan and Steven A. Hackley
University of La Coruna and University of Missouri-Columbia
Comparisons at the Missouri lab of prepulse effects on voluntary and
reflexive reactions have suggested that divergent mechanisms are
involved. The present study attempted to identify whether a
task-irrelevant prepulse speeds choice reaction time (RT) by
facilitating low-level motor pathways (which might be shared with
reflexes) or central, decision-level structures (which reflexes lack).
On each trial, the subjects (N=20) made a speeded left- or
right-hand keypress to the letter "S" or "T" if that stimulus was of
one size ("Go" trials), but withheld their response if it was of
another possible size ("No-go" trials). On half of the trials, a
task-irrelevant tone-pip accompanied the letter with a lead time of 30
ms.
On Go trials, choice RTs were reliably facilitated by these
accessory stimuli. Lateralized motor readiness potentials (LRPs) were
separately computed with time-locking to stimulus onset and to movement
onset. Comparisons showed that facilitation of RTs was due to
shortening of the time interval extending from stimulus onset until LRP
onset (Miller's Jack-knife test). The interval from onset of
lateralization until keypress was unaffected. A brief LRP was observed
on No-go trials, in the absence of EMG activation. This abortive
activation of motor cortex was also facilitated by the accessory
stimulus. The results converge with those of reflex-RT studies to
contradict the hypothesis that accessory stimulus effects on RT are due
to facilitation oflow-level motor pathways. This research was
supported by the Ministry of Education (Spain) and the National
Institutes of Health (U.S.A.).
Optimal recording of electric, acoustic, and visual blink reflexes:
Effects of EMG signal bandwidth and inter-electrode distance
A. van Boxtel, A.J.W. Boelhouwer, and A.R. Bos
Tilburg University
Blink reflexes are usually measured by integrating the orbicularis
oculi EMG signal. EMG signals are high-pass filtered to remove
low-frequency movement artifacts. Filtered responses are sometimes
small and difficult to detect which can bias experimental outcomes.
Mathematical models of the surface EMG signal predict that increasing
the inter-electrode distance will produce smaller high-frequency and
larger low-frequency spectral components with a net increase in signal
power. However, this may provide less reliable results because the
spectral shift to lower frequencies leads to a larger contamination by
low-frequency artifact components. We have studied the optimal EMG
recording bandwidth and inter-electrode distance in order to maximize
signal amplitude and minimize artifact effects. Electric, acoustic,
and visual blink reflexes were elicited in three different groups of 15
subjects. Fifty reflexes were elicited at irregular intervals during
the presentation of a cartoon film. Two pairs of electrodes were
applied on orbicularis oculi with inter-electrode distances of 12 and
36 mm. EMG signals were recorded with a bandwidth of 0.4-520 Hz,
digitally high-pass filtered with the -3 dB cut-off frequency
successively increasing from 4 to 92 Hz in steps of 8 Hz, and subjected
to spectral analysis. Low-frequency artifact components were
relatively larger for electric and acoustic than for visual blinks.
The optimal high-pass cut-off frequency was 28 Hz for electric and
acoustic reflexes and 20 Hz for visual reflexes, both for the large and
small inter-electrode distance. The total signal power was
systematically larger with larger inter-electrode distance.
The use of reflexes in chronopsychophysiology and in the study of
response inhibition
G.J.M. van Boxtel12, R.H.A.H. Jacobs1, M.W. van der Molen2, J.R.
Jennings3, and C.H.M. Brunia1
1Tilburg University, 2University of Amsterdam, 3University of Pittsburgh
Spinal reflexes are important for chronopsychophysiology because they
provide an additional time marker between the currently available
cortical (LRP) and peripheral (EMG) measures. They are particularly
important for the study of response inhibition, which is commonly
modelled by a "horse race", in which independent activation and
inhibition processes race for completion. This race is suspected to
finish very late in the information processing system, since response
inhibition is accompanied by cortical activation (as indexed by the
LRP), which does not lead to overt movement (as indexed by the EMG).
Hence it is interesting to study a neurophysiological system in between
the motor cortex and the effector muscles, such as the spinal cord.
Achilles tendon reflexes were evoked in an auditory Go/NoGo 50/50 task
involving a response with the right hand. In experiment I, reflexes
were evoked at 100, 200, 300, 400, 500, and 600 ms after the stimulus.
Experiment II consisted of two sessions, the first being equal to
Experiment I. In the second session, reflexes were evoked at latencies
relative to the mean reaction time of the first session. The results
indicated that reflexes increased both on Go and NoGo trials at 100 ms
after the stimulus. They then returned to baseline on NoGo trials, but
sharply increased on Go trials starting from 80-100 ms before the
response. These results show that Go and NoGo trials can be succesfully
distinguished at the spinal level. The use of reflexes for
chronopsychophysiology and response inhibition is discussed.
When does phonology meet semantics? ERP evidence for early semantic
processing
Cyma Van Petten, Susan Rubin, Elena Plante, and Marjorie Parks
University of Arizona
We established the "isolation point" for a set of auditory words - the
amount of acoustic information necessary to identify a word. Subjects
were presented with the first 50 ms of each word, or the first 100,
150, etc. ms (up to the end of the word) and asked to guess what they
were hearing. Mean word duration was 600 ms, but accurate word
identification was achieved with 350 ms of input on average. These
words were then used to complete spoken sentences, and ERPs were
timelocked to both word-onset, and to the isolation point. The
sentence-final words were either 1) semantically congruous, 2)
incongruous, but sharing initial phonemes with the expected word, 3)
incongruous, but sharing final phonemes (rhyming words), or 4)
completely incongruous. For example, "The highway was flooded so they
had to take a long DETOUR / DETAIL / CONTOUR / TABLE." All of the
incongruous conditions elicited larger N400s than congruous. The
congruity effect began at about 150 ms after the onset of completely
incongruous and rhyming words, but was delayed until about 350 ms in
the case of incongruous words with appropriate initial phonemes. The
congruity effect for words with appropriate initial phonemes began at
about the isolation point. For words with inappropriate initial
phonemes, the congruity effect began well before the isolation point.
These results suggest that the N400 congruity effect is timelocked to
what can be called the "discrepancy point" - the first point at which
acoustic input diverges from semantic expectations. The results
additionally suggest that semantic processing begins before a word can
be uniquely identified.
An ERP study of the effects of cueing and switching on the processing
of compound stimuli.
J.L. van Velzen1, A.A. Wijers1, D.Vorberg2, A. Heinecke2, L.J.M.
Mulder1, and G. Mulder1.
1University of Groningen, 2Technical University of Braunschweig
Visual information can be thought of as an hierarchy of properties: at
the most local level information about the smallest details is
represented, and at the most global level information about the object
as a whole. From several behavioral studies it appeared that attention
can be directed effectively to local or global features of a compound
stimulus (e.g. Kinchla, Solis-Macias & Hoffman, 1983, Perception and
Psychophysics, 33, 1-10).
In this study multichannel EEG recordings used to investigate the
temporal and topographical effects of precueing one level of a
compound stimulus and of switching attention between the two levels.
The behavioral results showed that more time is needed to switch
attention from the local to the global level than vice versa.
Furthermore, from the ERPs and the topographical distribution of
recorded activity it seemed that different brain structures were
involved, dependent on the direction of the switch. A parietal centre
of activation was found when subjects switched from local to global,
and more occipital activation when a switch was made from global to
local. The ERP-effects of orienting attention to the global level as
compared to orienting to the local level are evident in the
cue-stimulus interval as well as in the interval following the
presentation of the compound stimulus. The latter effects consisted of
a larger P1 amplitude and a smaller occipital and parietotemporal N1
amplitude for locally cued conditions.
From the results of this experiment it can be concluded that
zooming out involves a fundamentally different process than zooming
in. An alternative explanation would be that an additional process is
involved in processing the compound stimuli in this task, that
contributes to the effects found in this experiment. We investigated
the role of a negative priming mechanism as a possible candidate for
this additional process.
Resting EEG predicts performance in a subsequent vigilance task
Andrei Vedeniapin, John Rohrbaugh, Erik Sirevaag, and John Stern
Washington University School of Medicine
Individual differences in resting EEG were studied with the aim of
identifying features that might be premonitory of performance in a
subsequent vigilance task. Multi-channel EEG data were obtained from
13 subjects under eyes open conditions, after which subjects
participated in a continuous performance task lasting 50 min. The task
required subjects to monitor visually-displayed numerals to detect and
respond to occasional runs of three consecutive odd or even digits.
EEG spectral power was derived by FFT from an artifact-free 30 sec
period, with power partitioned into delta (1-4 Hz), theta (4-7.5 Hz),
alpha 1 (7.5-9.5 Hz), alpha 2 (9.5 to 10.5 Hz), alpha 3 (10.5 to 13
Hz), and beta 1 (13-18 Hz) bands. A coefficient of prevalence of slow
or fast alpha power was also calculated in terms of the normalized
difference between alpha 1 and alpha 3 power. A subjective measure of
sleepiness was obtained using the Stanford Sleepiness Scale,
administered before and after the vigilance task. Several features of
the initial resting EEG were correlated significantly with subsequent
performance. Subjects who performed accurately showed a prevalence of
right occipital alpha 3 spectral power. Increased theta and delta power
was observed in subjects with the fastest reaction times. Right
occipital alpha 1 power (but not slower activity) was associated with a
large increase in sleepiness during the vigilance task. In sum, these
data indicate that features of the resting EEG can be used to predict,
to some extent, subsequent performance in a sustained attention task.
Supported by FAA Contract 94-G-015.
CNV is largest after partial cueing
Rolf Verleger, Bernd Wauschkuhn, Edmund Wascher, Torsten Niehoff, and
Peter Trillenberg
Medical University of Luebeck
CNV was recorded in an S1-S2 task where S2 could signal one of four
alternative responses: right keypress, left keypress, looking right,
looking left. S1 provided full or no or partial information about the
response, with partial information specifying either the side of
movement (right or left) or the effector system (hand or eye). The
paradigm worked well: Responses were fastest after full infomation and
slowest after no information. If reflecting movement preparation, the
pre-S2 CNV should be largest after full information and smallest after
no information. If reflecting expectancy of information, the pre-S2 CNV
should be largest after no information. However, in contrast to both
assumptions, CNV was largest after partial information. This finding
was replicated in a second experiment. Topography (19 recording sites)
did not differ between conditions, always displaying a Cz maximum.
Therefore CNV appears to reflect the same process in each cueing
condition. Assuming this process to be movement preparation, the large
CNV after partial information might reflect subjects' simultaneously
preparing two movements (even antagonistic ones, e.g. looking right and
left). This conclusion would support part of Miller's position about
partial cueing in his debate (J. Exp. Psychol. HPP 1982-85) with Reeve
& Proctor (cueing indeed affecting movement preparation) and part of
Reeve & Proctor's position (cueing having benefits for any pair of
movements that share a common code). Besides, a constant
posterior-parietal asymmetry was found (PO6 > PO5), perhaps due to the
eye-hand coordination needed in this task.
Order effects related to habituation in the central and peripheral
nervous systems
Lara Versluys1, Tomas Furmark1, Hakan Fischer1, Gustav Wik2, and Mats
Fredrikson1
1Uppsala University, 2Karolinska Institute
Spider phobics and non-fearful subjects viewed spider and neutral
video's (parkscenes) presented twice while regional cerebral blood flow
(rCBF) was measured using positron emission tomography with [15-O]
butanol as tracer. Autonomic indices included heart rate and
electrodermal activity. Order effects were studied by substractive
imaging methodology. An order effect was observed in non-fearful
subjects viewing spider but not park scenes. A significant rCBF
decrease was evident in the primary and secondary visual corticies (
Brodmann areas 17, 18 and 19 ), with a relatively greater decrease in
the right than the left hemisphere. This order effect might reflect
learning related to habituation processes since heart rate decrement
was also present. This indicates parallel central and peripheral
processes at a group level. Correlations between rCBF order effects and
heart rate decrement suggest that individual differences in heart rate
habituation correspond to individual differences in central neural
activity.
Autonomic mechanisms underlying the cardiac defense response in humans
Jaime Vila1, M. Carmen Fernandez1, M. Nieves Perez1 and Gustavo Reyes2
1University of Granada, 2University of Jaen
The sympathetic and parasympathetic mechanisms underlying the heart
rate response to intense auditory stimulation (the so-called cardiac
defense response) were concurrently re-examined in three studies which
used different autonomic indices of cardiac control: Pulse Transit Time
(sympathetic), Stroke Volume (sympathetic) and Respiratory Sinus
Arrhytmia (parasympathetic). The results of the three studies clearly
confirm the description of the heart rate response as consisting of
four consecutive components: A first and short acceleration that peaks
around second 3, followed by a deceleration that generally surpasses
that of baseline, and a second and long acceleration that peaks around
second 30, ending with a second deceleration. Analysis of the autonomic
space underlying the observed heart rate changes shows a sequencial
pattern of sympathetic-parasympathetic interactions along the four
components of the response with co-inhibition (first acceleration),
co-activation (first deceleration), sympathetic
activation-parasympathetic inhibition (second acceleration) and
sympathetic inhibition-parasympathetic activation (second
deceleration). The finding of a vagal dominance during the first two
components of the response, restraining the sympathetic influences, and
a reciprocal interation during the last two components, with
sympathetic dominance, gives support to the idea that the defense
reaction in natural settings follows a sequential process with initial
phases in which attentional factors predominate -directed to detailed
processing of the stimulus- and later phases in which motivated actions
predominate -directed to overt behaviors of fight or flight-. The
implications of these results are discussed in the context of
traditional views on orienting and defense.
Imaging functional brain connections in stimulus processing revealed by
evoked coherence of EEG components
Hans-Juergen Volke, Boris M. Velichkovsky, Peter Dettmar, Peter Richter,
Matthias Rudolf, and
Torsten Klemm
Dresden University of Technology
Multichannel EEG was derived in three stimulus presentation
experiments: 1. Counting target tones within an oddball- paradigma; 2.
Solving different types of visually presented chess tasks. 3.
Categorization of written words at different levels of processing
(Craik & Lockhart, 1972). EEG records were continuously decomposed into
the "classical" components beta, alpha, theta and delta, using
time-variant spectral analysis (Volke & Dettmar, 1990). For these
components evoked coherences were computed upon component- related post
stimulus intervals - especially from .5 to 2.5 mean wave lengths.
Results obtained suggest that stimulus processing of the brain implies
a subtle cooperation of specific areas which is highly structured in
frequency, space and time. In all three experiments, highly significant
task-specific patterns of evoked coherences emerged. As a tendency,
task-related differences of evoked coherences mostly occured within the
slower frequency bands (theta and delta), and more complex processing
modes involved more left-temporal and frontal areas of the cortex.
Generally, evoked coherences of the EEG seem to provide insights into
some new aspects of the functioning of the brain. A basic
methodological problem will be discussed: As evoked coherences appeared
to be component-specific, the question arises which physiologically
defined components the EEG consists of, which is not answered as yet.
It will be shown that the normal EEG may be fully represented by only
four components of variable frequency and amplitude, which are in good
accordance with the classical components from delta to beta. Results
obtained on the basis of these components will be compared with those
obtained by alternative frequency resolutions.
Chronic work stress and the risk for cardiovascular disease in
sedentary males
Tanja Vrijkotte, Eco de Geus, and Lorenz van Doornen
Vrije Universiteit
Recent epidemiological research has shown that a high level of work
stress is associated with an increased risk for cardiovascular disease.
The pathophysiological mechanisms underlying this association remain
unclear. The present study tests to what extent work stress is
associated with elevations in the so-called Insulin Resistance
Syndrome, or syndrome "X" variables, i.e.
cholesterol/lipoproteinfractions, plasminogen activator inhibitor,
fibrinogen, glucose, and insulin.
From a group of 500 sedentary middle-aged males, the group of 50 men
with the
highest work stress was selected and compared to the group of 50 men
with the lowest level of work stress. Work stress was defined,
according to Siegrist and coworkers(Siegrist et al., Soc. Sci. Med.,
31, 1991), as a recurrent imbalance between high effort and low
reward. Blood samples were taken at the beginning, in the middle and
the end of the workweek. Intra-week effects were found for glucose
only, with highest glucose levels at the start and lowest glucose
levels at the end of the week. On all three days, the high work stress
group showed higher triglyceride and lower HDL cholesterol levels than
the low work stress group. No group effect emerged on glucose, insulin
or the fibrinolytic parameters. However, subjects have only been
partially analysed (N=62) for these latter variables. Full results will
be presented at the conference. These will be discussed within the
framework of the prospective epidemiological connection between chronic
work stress and atherosclerosis and thrombosis,
Physiological indices of mental effort during a warned choice reaction
time task: A comparison between heart rate variability and corrugator
EMG activity
W. Waterink, A. van Boxtel, and I.J.T. Veldhuizen
Tilburg University
Physiological indices of mental effort may be sensitive to demands on
particular resources or may reflect aggregate demands on all
resources. Heart rate variability (HRV) within the 0.07-0.14 Hz
frequency band and corrugator EMG activity have repeatedly been claimed
as measures with sensitiv- ity to aggregate demands. In the current
study, these measures were compared during the performance of a
difficult warned visual choice reaction time task. The reaction signal
was presented 4 s after a warning signal. Repetition rate of trials
was varied across three 10-min trial blocks which were presented in a
counterbalanced order and preceded by a 5-min baseline period. To
study the time-on-task effect, baseline period and trials blocks were
presented a second time. Achievement motivation was manipulated by
giving 20 subjects a combination of knowledge of results and monetary
reward whereas 20 control subjects did not receive incentives. It was
expected that working rate, time-on-task, and incentives would induce
higher compensatory mental effort reflected by larger corrugator EMG
responses and reduced HRV. The task had a significant overall effect
on EMG activity but left HRV unaffected. Working rate, time-on-task,
and incentives significantly facilitated EMG responses but had no
effect on HRV. The experimental manipulations produced several
tendencies to increasing rather than decreasing HRV. This might be
related to the relatively strong parasympathetic control of cardiac
responses during warned reaction time tasks. We conclude that during
such tasks corrugator EMG responses better reflect the mobilization of
aggregate mental resources than does HRV.
EEG and caffeine: A comparative spectral and dimensional analysis
Paul A. Watters
Mental Health Research Institute of Victoria, Australia
Research into the observed effects of pharmaoclogically active agents
on EEG power spectra has yielded inconsistent results regarding
relative and absolute changes in power as a function of dosage. A
recent study (N=10) examined the effects of graded doses of caffeine
(100 mg, up to 600 mg) on EEG power, and on EEG dimensionality (as
determined from the application of the Grassberger-Procaccia
algorithm). Caffeine appears to have an optimising effect on caffeine
dimension, decreasing initially (up to 400 mg), then increasing
(400-600 mg). Results are interpreted in the context of both classic
theories of arousal (e.g., Yerkes-Dodson Law), and current thinking on
the dynamics of cortical activation.
Lateralized cortical activity due to preparation of saccades and finger
movements: A comparative study
Bernd Wauschkuhn, Edmund Wascher, and Rolf Verleger
Medical University of Luebeck
The topography and time course of event-related asymmetries of the EEG
associated with horizontal saccadic eye movements and finger movements
was compared in a four-choice response task, where the subjects had to
respond to the imperative stimulus (S2) by moving the right or left
index finger or by making a saccade to the right or the left. The cue
stimulus (S1) contained full, partial, or no information about the
direction and the effector. In case of finger movements three distinct
lateralisations were found: 1) increased negativity over the motor
cortex contralateral to the future movement direction, 2) increased
contralateral negativity at temporo-parietal sites beginning 200 after
delivery of the directionalinformation and 3) increased ipsilateral
negativity at temporo-parietal sites beginning 350-500 ms after
delivered direction and effector information. The Early Temporo-
Parietal Lateralisation was also visible in case of saccadic eye
movements and in case of effector-unspecific directional information.
Before saccadic eye movements no other distinct lateralisation could be
observed at any recording site. In sum, lateralised cortical activities
due to preparation processes for finger movements and due to
effector-unspecific processing of directional information for motor
preparation by the posterior parietal cortex could be demonstrated,
whereas no distinct lateralisation due to preparation for saccadic eye
movements was visible.
Respiratory sinus arrhythmia from child- to adulthood; What happens in
between?
E.J.M. Weber, R.J.M. Somsen, and M.W. Van der Molen
University of Amsterdam
Developmental changes in respiratory sinus arrhythmia were examined in
two experiments in which heart rate and respiration were recorded from
subjects in rest and attention demanding conditions. Three age groups
participated in the first experiment; 5-, 7-, and 9-year olds. These
children performed standard oddball and reaction time tasks. The
results from this experiment revealed a depression of spectral power in
the RSA band during task performance relative to baseline. The
reduction in RSA did not discriminate between age groups. In the second
experiment, the age range was expanded by recording heart rate and
respiration from two groups of children, 5-, 12-year olds, and adult
volunteers. Measurements were taken in rest and during a habituation
task. The results were similar to the data from the first experiment in
showing a reduction of spectral power in the RSA band during task
performance relative to rest. In contrast to the first experiment,
however, RSA decreased significantly with age. In addition, RSA peak
amplitude shifted to lower frequencies with age. Interestingly, RSA
peak frequency corresponded to respiratory frequency for the older
children and adults but not for the youngest age groups. Subsequent
coherency analysis yielded lower values for the 5-year olds compared to
the older age groups. These findings may suggest that the
respiratory-heart rate coupling does not reach mature levels during
childhood. This finding might have important implications for the use
of RSA as a noninvasive tool to examine the status of the nervous
system in clinical groups.
Prepulse inhibition and habituation of skin conductance responses in
schizophrenics: Neuroleptic drug effects
Almut Weike1, Jutta Globisch1, Alfons Hamm1, and Ulrike Bauer2
1University of Greifswald, 2University of Giessen
Startle response magnitude is substantially reduced when a
non-startling stimulus (prepulse) shortly precedes the startle
eliciting stimulus. This so called prepulse inhibition is impaired in
schizophrenic patients. The present study was designed to replicate and
extend the findings, focussing on the influence of neuroleptic
medication on this process. Moreover, it was investigated, how
habituation of the electrodermal orienting activity was influenced by
different drugs. Thirty-six schizophrenic patients (12 unmedicated)
participated in the experiment. Twelve healthy controls were recruited
from hospital and laboratory staff. The prepulse was a 85 dB(A) 1000 Hz
tone (20 ms duration), which preceded the startle stimulus (50 ms burst
of 105 dB(A) white noise) by 30, 60, 120, or 240 msec. As expected,
while control subjects showed a clear reduction in startle magnitude
following prepulse presentation, prepulse inhibition was significantly
impaired in unmedicated schizophrenics. Unmedicated patients also
showed significantly less habituation of skin conductance responses. By
contrast, medicated patients showed prepulse inhibition and
electrodermal response habituation comparable to that shown by the
controls. This medication effect was also apparent when some of the
patients from the unmedicated condition were tested after receiving
neuroleptic medication. Once medicated, these patients showed larger
prepulse inhibition and increased habituation of electrodermal
responses.
Role of spatial abilities in motion sickness susceptibility
S.E. Weinstein, E.R. Muth, J.T. Andre, E. Jarret, R.S. Stern, H.W.
Leibowitz, and W.J. Ray.
Pennsylvania State University
The primary objective of this study was to determine whether
motion sickness susceptibility is related to individual
differences in spatial abilities. Motion sickness susceptibility was
determined by exposing 45 subjects to a rotating optokinetic drum and
recording their subjective symptoms. Electrogastrograms (EGGs) and
cardiac interbeat intervals (IBIs) were also recorded. During a second
session, subjects were tested on three types of spatial tasks; the
water level test, a mental rotation test, and the rod and frame test.
No systematic relationship was found between mental rotation or the rod
and frame task and symptoms of motion sickness. However, subjects
susceptible to motion sickness did significantly worse on the water
level test than those who were not susceptible (p < .01). EGG results
indicated that susceptible subjects showed a significantly greater
increase in percentage of gastric tachyarrhythmia, abnormal gastric
myoelectric activity usually associated with nausea, from baseline to
drum rotation than did the non-susceptible subjects. Vagal activity,
as estimated from variability in the IBIs using the algorithm of Porges
and Bohrer (1990), showed a significantly greater decrease from
baseline to drum rotation for susceptible subjects compared to
non-susceptibles (p < .05). In conclusion, subjects who performed
poorly on the water level task, which has been considered a measure of
an internal sense of horizontality, were also more susceptible to
vection induced motion sickness.
Cardiovascular patterns associated with threat and challenge
appraisals: Individual responses across time
S. Weinstein1, K.S. Quigley1, and L. Feldman Barrett2
1Pennsylvania State University and 2Boston College
The purpose of this study was to examine individual cardiovascular
patterns associated with cognitive appraisals over four arithmetic
tasks. Previous studies demonstrated distinct patterns associated with
threat and challenge appraisals across groups of subjects. Threat
appraisals (high stress; low coping ability) are associated with modest
increases in heart rate (HR), cardiac output (CO), and pre-ejection
period (PEP), and increases in total peripheral resistance (TPR).
Challenge appraisals (mild to moderate stress; high coping ability) are
associated with larger increases in HR, CO, and PEP, and decreases in
TPR (Tomaka et al., 1993). In the current study, we extend these
results by examining threat and challenge appraisals within individuals
across time. Subjects completed four verbal arithmetic tasks with
ratings of stressfulness and coping ability made before and after each
task. Appraisal ratios were computed by dividing stressfulness ratings
by coping ratings. The relationships between changes in individuals'
appraisals and cardiovascular patterns over the four task epochs were
analyzed using hierarchical linear modeling (HLM) which permits
separation of between- and within-subjects variance. Change scores
from baseline for the final minute of each task were computed for PEP,
TPR, interbeat interval (IBI; inverse of HR), and CO. Post-task threat
appraisals were associated with smaller decreases in PEP (p < .02), and
larger increases in TPR (p < .05). Changes in IBI and CO were
nonsignificant. These data extend previous results for PEP and TPR
using individual-level analyses of task appraisals across four tasks,
and demonstrate the use of HLM for psychophysiological studies.
EEG measures of differential brain activity: Before, during, and after
the perception of apparent as opposed to actual movement
Erik D. Welch, John Lagomarsino, and John M. Morgan
Humboldt State University
The Autokinetic effect is a visual phenomenon of illusory movement,
experienced when a small, stationary spot of light is seen to move
across a contrasting and patternless background. Outflow theory states
that autokinesis is due to a mismatch between the retinal image signal
and the eye motion, outflow, signal. It is theorized that involuntary
directional shifts of the eye are not monitored by the brain.
Voluntary motor commands generate sensory expectations of movement of
the visual field which are efference copies or corollary discharges
This expectation cancels out the afferent signals which result when the
visual field is moved However proprioceptors, which signal the amount
of stretch in muscle, have been found in human extra-ocular muscles
which weakens the outflow theory.
Event Related Potentials (ERPs) were recorded from four
conditions: darkness (no visual stimulus), autokinesis (illusory
movement), horizontal movement (2 cm/sec), and vertical movement (2
cm/sec). These conditions were presented in blocks of ten, in random
order 6 times each, for a total of 240 trials per subject.
A P3 component was found in all of the conditions, along with
the Bereitschaftspotential (BP) and Motor Potential (MP).
Differences were found however, in the latency to the subjects
response, suggesting subjects confidence level acting as a confound in
the amplitude of the components. Differences were found between the
darkness condition and all other conditions, supporting the validity of
Outflow theory. Results are discussed in reference to relevant
perceptual and ERP theories.
The effects of stress and muscle activity on P50 suppression
Patricia M. White, Cindy M. Yee, Maria Nazarian, Halle Jones, and
Valerie Gilman
University of California, Los Angeles
The ratio of P50 amplitude to paired clicks has been suggested as a
preattentional gating response that is impaired in schizophrenia.
Previous work assessed the relative effects of attention and anxiety on
the P50 suppression ratio in unselected controls, suggesting that P50
suppression is unaffected by attentional manipulation but diminished
during an oral mental arithmetic stressor. In this study, several
factors which might explain reductions in P50 suppression by the oral
mental arithmetic stressor were considered.
Ten tasks which manipulated muscle activity, auditory competition,
cognitive demand, and levels of effort and anxiety were administered
while subjects were presented with paired clicks. Preliminary results
suggest that reductions in P50 suppression during performance of the
oral mental arithmetic stressor are unlikely to result from either
competing cognitive or auditory tasks. Competing cognitive tasks
performed without muscle activity showed no effect on P50 suppression
while competing auditory tasks reduced P50 amplitude but did not
influence the P50 suppression ratio. Tasks which varied muscle
response were associated with an enlarged P50 suppression ratio
although diminished P50 suppression did not occur in all subjects.
Within tasks in which effort was manipulated, self-ratings of effort
correlated positively with the P50 suppression ratio. Results of tasks
rated as anxiety-provoking suggest that anxiety also may reduce P50
suppression. The post-auricular reflex and heart rate were found to
correlate with P50 suppression and with self-ratings of effort and
anxiety. These findings are discussed in relationship to P50
suppression research on schizophrenia.
Heartbeat detection and the experience of emotions
Stefan Wiens, Elizabeth Mezzacappa, Stephen Palmer, Anil Chacko, Marc
Lingat, and Edward S.
Katkin
State University of New York at Stony Brook
Self-perception of physiological activity has been postulated to play
a crucial role in the experience and expression of emotion (James,
1884, Mind, 188-205; Schachter & Singer, 1962, Psychological Review,
379- 399). However, there is scant empirical work on the relation
between self-perception of visceral activity and the expression and
experience of emotion (Ferguson & Katkin, 1996, Biological Psychology,
131-145; Katkin, 1985, Psychophysiology, 125-137). In the present
study, 52 undergraduates (19 males) were classified as good (n = 10) or
poor (n = 42) heartbeat detectors using a modified Whitehead
discrimination procedure (S+ = 200, S- = 500). Subjects were then
presented with two video clips representing each of three different
emotional valences (amusement, anger, fear). After each of the six
clips, self-reported affective responses to the clips were measured on
two orthogonal 9-point scales indicating arousal level and valence,
respectively. Electrodermal activity was measured at baseline and
during each video clip. It was hypothesized that good heartbeat
detectors would experience more intense emotional arousal than poor
heartbeat detectors, irrespective of actual arousal level, but would
not differ in ratings of the valence of the experienced emotions. As
predicted, good detectors reported higher levels of arousal than poor
detectors across all three emotional valences, F(1,46) = 8.89, p < .01,
using electrodermal activity for each clip as a covariate to control
for physiological arousal level. No differences were found on valence
ratings between the two groups on any of the emotions. These results
support the view that heartbeat detection plays a role in the
experience of emotional intensity.
Ambulatory assessment of self-report, autonomic, and respiratory
responses during phobic anxiety
Frank H. Wilhelm and Walton T. Roth
Stanford University School of Medicine and VAPA Health Care System, Palo
Alto
Although physiological measures are recognized as theoretically
important in assessing anxiety, their practical utility has been
questionable. We undertook to evaluate physiological indices of
anxiety and to test specific anxiety theories in 14 flight phobics and
15 sex- and age-matched controls who were willing to take a short
commercial flight.
Subjects wore a light, compact monitor that recorded
cardiovascular, electrodermal, and respiratory activity. They
rated themselves on a battery of self-reports of mood and symptoms
before, during, and after the flight. The benefits of baseline
adjustment and transformation for all variables, and the adjustment of
heart rate by ventilation to give "additional heart rate" were
calculated.
The variables that best distinguished the groups during flight
were self-reported anxiety and additional heart rate. The first
classified subjects with an accuracy of 90% and the second with an
accuracy of 79%. Although respiratory rate and minute volume,
indicators of hyperventilation, did not distinguish groups, phobics
paused during inspiration more than controls. Skin conductance
fluctuations were increased and respiratory sinus arrhythmia was
decreased in the phobics. Awareness of physiological changes was
indicated by significant correlations between skin conductance level
and reported sweating, but not between respiratory measures and
reported shortness of breath or between heart rate and reported heart
pounding or racing.
Our results demonstrate that ambulatory monitoring of multiple
physiological systems is feasible in phobic situations outside the
laboratory. Several measures of heart rate proved to be powerful
indices of anxiety. Specific breathing irregularities characterized
phobics when anxious.
Additional heart rate: Application and validation under ambulatory
conditions
Frank H. Wilhelm and Walton T. Roth
Stanford University and VAPA Health Care System, Palo Alto
Physical activity produces physiological activation like that
produced by anxiety. One way of avoiding confusion is to exclude
epochs containing physical activity. Alternatively, the anxiety
component of heart rate (HR) can be calculated as the HR above that
predicted by oxygen consumption. Our innovation in this study was to
substitute minute ventilation (Vmin) for oxygen consumption in an
ambulatory setting, calculating additional heart rate (HRadd) from the
relation between Vmin and HR during an exercise test.
26 participants with flying phobia and 15 nonanxious controls were
physiologically monitored while bicycling under 3 different loads,
while walking (leaving the hospital, entering a plane), and during
flight. Individual regression equations relating HR to Vmin were
derived from the bicycling (mean R square=.80). Vmin did not differ
between groups at any point. Unadjusted HR was not significantly
different between phobic participants and controls leaving the hospital
(119/114 bpm, p>.38) or entering the plane (117/110 bpm, p>.25).
However, although HRadd was not different leaving the hospital (7.9/8.6
bpm, p>.75), it was entering the plane (18.0/9.9 bpm, p=.01),
reflecting the greater anxiety in the phobic participants. Even though
physical activity was minimal during flight, HRadd was also superior to
HR for indexing group differences there. In general, our results
suggest that this methodology could be useful in assessing
agoraphobia.
Psychophysiological correlates of multiple task performance
Glenn F. Wilson1, Lisa Fournier2, and Carolyne R. Swain3
1Armstrong Laboratory, 2Washington State University, 3Logicon Technical
Services, Inc.
Since multi-task paradigms approximate real world environments, the
nature of psychophysiological responses to the cognitive demands of
complex operations is of both theoretical and applied importance. By
the same token, multiple psychophysiological measures provide an
exceptional means for delineating the relationships between multi-task
demands and performance. In this study, the Multi-Attribute Task
Battery was used to generate single and multi-task scenarios. An
auditory communication task served as the single task and was combined
with visual monitoring and tracking to provide a multi-task with four
levels of difficulty. Performance and subjective workload ratings as
well as ECG, EEG, EOG and respiration were recorded from ten subjects
(4 male, 6 female). EEGs recorded from 58 active sites were corrected
for eye artifacts and submitted to current source density and FFTs
procedures. The relative power in five bands were statistically
compared. Heart rate (HR), heart rate variability (HRV), eye blink
rate (BR) and respiration rate (RR) were also evaluated. Performance
and workload ratings evidenced the predicted changes due to number of
tasks and difficulty. HR increased and HRV decreased significantly
between single and multiple tasks and in response to the most difficult
condition. BR decreased and RR increased significantly during
multi-task conditions. With regard to the EEG, multi-task conditions
resulted in increased theta (central and parietal) and beta (frontal)
and decreased alpha (parietal and occipital) compared to single task
conditions. Results are discussed in terms of the sensitivity of
psychophysiological measures to different aspects of mental workload.
Effects of tone-cued fear and pleasant imagery on reaction times to
early probes, heart rate, and skin conductance
Charlotte vanOyen Witvliet, Jason R. Robinson, Georgia Panayiotou, and
Scott R. Vrana
Purdue University
This study examined the effect of imagery cues on reaction times
(RTs) to auditory probes. Imagery effects on heart rate and skin
conductance were also assessed. In each of 6 blocks, participants (24
males, 22 female) imagined themselves in fear and pleasant relaxation
situations for 6-second trials when cued by high or low tones. Imagery
trials were separated by 3 to 6 six-sec intervals of a "think 'one'"
control condition cued by medium frequency tones. Materials were
counterbalanced across subjects. For the secondary task, RT probes
(100 ms of 64 dB white noise) were presented 120 ms, 500 ms, or 2000 ms
after tone (600 ms, 69 dB) onset. Participants were instructed to
press a button with their dominant thumb as soon as they heard the RT
probe and immediately resume their primary task. Overall, as RTs were
probed further away from tone onset, RTs were significantly faster.
When probes occurred 2000 ms after tone onset, imagery and "think
'one'" control RTs did not differ. However, at 120 and 500 ms, RTs
were significantly slower for probes that occurred during fear and
pleasant imagery tones than during control tones, suggesting that
imagery cues demanded more processing resources than the control
condition cue. At 120 ms, RTs were significantly slower during fear
than pleasant imagery tones, indicating that fear cues demanded more
processing capacity at this early interval. Paralleling previous
studies, heart rate was significantly faster during fear, and skin
conductance tended to be higher during fear than pleasant conditions.
The emotional impact of instrumental music on affect ratings, facial
EMG, autonomic measures, and the startle reflex: effects of valence and
arousal
Charlotte van Oyen Witvliet and Scott R. Vrana
Purdue University
Participants (31 males, 31 females) listened to prerecorded
instrumental music that varied in emotional valence and arousal. Music
was selected based on ratings by an independent sample. Each subject
first listened to and rated 16 pieces of music in terms of valence and
arousal. Then the subject listened to 51 counterbalanced trials. Each
trial consisted of 26 sec of music followed by 10 sec during which the
subject was instructed to continue to experience the emotion expressed
in the music. A tone then signaled the subject to relax and "think
'one'" to clear the emotion and music from the subject's mind. After
the last trial, subjects re-rated the music. Facial EMG, heart rate,
and skin conductance were measured during and after the music. The
acoustic startle reflex (for 25 males, 23 females) was probed at 3.5,
5, or 6.5 sec after music offset. Participant ratings clearly
differentiated the negative and positive as well as the low and high
arousal materials both at the beginning and end of the experiment.
Corrugator EMG was higher during negative music and zygomatic EMG was
higher during positive music. Orbicularis oculi EMG, heart rate, and
skin conductance were greater during high arousal music. The acoustic
startle magnitudes in this music paradigm did not match the patterns
typically obtained in emotion research. During imagery, high arousal
facilitates the startle. However, in this study, startle magnitudes
were significantly larger for low compared to high arousal affect
conditions, and valence did not reliably influence startle magnitudes.
Emotional imagery and the visual startle reflex: Negative valence and
high arousal independently increase magnitudes
Charlotte van Oyen Witvliet and Scott R. Vrana
Purdue University
This study used visual (light flash) probes to prompt the startle
reflex during emotional imagery that systematically varied in affective
valence and arousal. Participants (24 males, 22 female) completed 6
blocks of tone-cued imagery with their eyes closed. In each block,
they imagined themselves in two different emotional situations during
8-second trials when cued by either a high or low tone. Imagery trials
were separated by 3 to 6 eight-sec periods of tone-cued relaxation.
The results replicate findings obtained with an acoustic startle probe
(Witvliet & Vrana, Psychophysiology, 1995). Here, visually-probed
startle magnitudes were significantly larger both during negative
(fear, sadness) compared to positive (joy, pleasant relaxation) imagery
and during high arousal (fear, joy) compared to low arousal (sadness,
pleasant relaxation) imagery. The influence of affective arousal was
even more potent than valence in modulating startle magnitudes.
Participants were also asked to estimate how often the visual startle
(flash) occurred during each type of imagery (fear, sadness, joy,
pleasant relaxation). Paralleling startle results, participants
estimated that the flash occurred significantly more often during
negative versus positive and high arousal versus low arousal imagery,
even though all types of imagery were probed with the light flash
equally often. Consistent with previous findings, heart rate was
significantly faster during high compared to low arousal imagery.
Heart rate variability in PTSD: Mid-frequency power is inversely
related to trauma severity and nightmares
Steven H. Woodward and M. Michele Murburg
National Center for PTSD
We measured heart rate variability (HRV) during baseline sleep in 46
combat-related posttraumatic stress disorder patients and eight
combat-exposed controls. All subjects were unmedicated and, in
particular, were free of beta-blockers and related hypertension and
cardiac medications. Three nights of continuous ECG were continuously
digitized at 125 Hz and heart period spectra calculated from demeaned,
detrended and windowed instantaneous heart period time series. The
latter were 30 seconds in duration and corresponded to manually-scored
sleep epochs. Consistent with earlier reports, REM sleep was observed
to be associated with elevated power at low and mid-frequencies and
reduced power in the high frequency band. HRV at all frequencies
tended to be lower in PTSD patients as compared to combat controls, but
these differences did not achieve significance. HRV was independent of
subjective sleep quality and sleep continuity. In contrast, low and
mid-frequency heart rate variability during non-REM sleep was reduced
in patients reporting 1) more combat exposure (Combat Exposure Scale;
Keane et al, 1989) (Pearson r's = -0.299 to -0.381, p < 0.04 to
0.009), and 2) more nightmares (assessed by combining the two
nightmare-related items from the Mississippi Scale of Combat-Related
PTSD, Keane et al, 1988; Pearson r = -0.379 to -0.391, p < 0.009 to
0.007). Within the control group, a similar relationship was observed
between and HRV and trauma exposure (Spearman r = -0.81, p < 0.05), but
not nightmare symptomology. These data suggest that heart rate
variability offers a valuable perspective on biological adaptations to
extreme stress in humans. More specifically, they suggest that trauma
exposure and nightmare symptomology may together be associated with
long-term modifications of sympathoneural cardiac regulation.
Effects of prehabituation of the prepulse on startle eyeblink
modification
Jonathan K. Wynn 1, Anne M. Schell 1, and Michael E. Dawson 2
1 Occidental College, 2 University of Southern California
It is generally believed that prepulse inhibition of the startle
eyeblink in passive attention tasks, where the subject is not
instructed to attend to the prepulses, is a truly automatic process. If
this is so, then prepulse inhibition should not be affected by
prehabituation of the prepulse, which reduces orienting to the
prepulse. Thirty-nine college student participants were randomly
assigned to two groups, one which received 30 presentations of a 5 s
tone stimulus and one which received 3 presentations of the tone
intermixed with 27 presentations of a light. Immediately following
these trials, the tone was used as a prepulse in a startle blink
modificationImmediately following these trials, the tone was used as a
prepulse in a startle blink modification noninstructed attention
paradigm with lead intervals of 60, 120, and 2000 ms, using an auditory
startle stimulus. Prehabituation was highly effective in reducing the
skin conductance OR to the tone by the beginning of the startle blink
modification trial series. Significant prepulse inhibition was observed
in both groups at the 60 and 120 ms probe positions, and significant
facilitation was observed in both groups at the 2000 ms probe
position. However, the prehabituation group and the no-prehabituation
group did not differ in either the amount of prepulse inhibition or
later facilitation that was seen. These results suggest that in a
passive attention paradigm, both prepulse inhibition and long lead
interval facilitation reflect the action of automatic (preattentional)
as opposed to controlled processes.
Effects of attention on P50 gating in schizophrenia
Cindy M. Yee, Patricia M. White, and Keith H. Nuechterlein
University of California at Los Angeles
Abnormalities in attention and sensory perception have characterized
models of schizophrenia since its first clinical description. Recent
advances suggest that the cognitive fragmentation and stimulus overload
observed in schizophrenia may be related to an inability to filter or
gate information. Freedman et al. (1987, Schizophrenia Bulletin, 13,
669-678) demonstrated that in normal subjects, the P50 component of the
auditory ERP to a second click shows gating or suppression relative to
the response elicited by the first click when the two audio clicks are
delivered 500 ms apart. In contrast, schizophrenic patients often fail
to exhibit P50 suppression, suggesting a loss of normal inhibition or
gating. For gating to be inferred accurately, changes in P50 amplitude
must result from inhibition rather than from fluctuating attention. To
examine such a possibility, Jerger, Biggins, & Fein (1992, Biological
Psychiatry, 31, 365-377) manipulated the salience of the second click
and found that while N100 was profoundly influenced by attention,
neither P50 amplitude nor its suppression were affected. The present
study adapted the paradigm developed by Jerger et al. to examine the
effects of attention on P50 suppression in schizophrenic patients.
N100 amplitude followed the predicted pattern with a diminished
response to the second click when attention was directed to the first
click but an enhanced response to the second click when attention was
directed there. Analyses of P50 suppression data suggest that a subset
of patients may be responsive to attentional manipulations depending
upon sub-classification of patient diagnosis (i.e., paranoid,
disorganized, or undifferentiated schizophrenia).
The role of psychophysiological traits in the process of the
biobehavioral therapy in patients with labile and stable hypertension
V.V.Zakharova, E.Sokhadze, O.Trofimov, and S.Kasjanova
Siberian Branch of Russian Academy of Medical Sciences
The goal of this study was the specification of the role of personal
psychophysiological traits in the pathogenesis of the stages and forms
of development of hypertension.
Biobehavioral therapy with temperature and EMG biofeedback (BFB) was
administered to 42 hypertensive patients. Before and after the course
of BFB they were tested by Mini-Mult inventory, Cook-Medley hostility
scale and Spilberger's test of anxiety.
Patients with labile hypertension (high systolic blood
pressure with elevated stroke volume and heart rate and normal
peripheral resistance) were characterized by higher tone of the somatic
muscles and normal skin temperature. EMG BFB training was more
effective as compared to temperature, and was accompanied by
decreased anxiety and fear.
Patients with stable hypertension (high diastolic blood pressure with
increased total peripheral resistance with normal or even decreased
cardiac output) demonstrated comparatively lower baseline temperature
of the skin with mild EMG tone. Successful temperature BFB training led
to decrease of diastolic blood pressure, and also lowered aggressiveness
and hostility.
The results of this study show that peculiarities of the personal
profiles determine variations in psychophysiological reactivity and
affect development of hypertension. Perfectly selected
biobehavioral therapy enhances correction of the pathological changes
and prevents their further progress.